[Freo-1]

For the past year, I've had the Devialet Expert Pro 250 as the primary setup.  Although I've tried a number of other options, I always come back to the Expert Pro 250.  It has better specs than just about any other amp setup available at any price.  Was able to afford it by sending in a D-Premier back to Devialet for upgrade. 


By pure luck, stumbled onto a second Expert Pro for a price that was just too good to pass up.  Here are the specs:

• Power: 2x1000 Watts RMS under 6Ω
• Distortion at full power: 0.00025% THD+N, 0,0001% (10W / 6Ω),
• Distortion at 10 watts: 0.0001%
• Distortion at 10 V: THD+N, 0.00025% THD+N
• SNR: 133 db
• Output Impedance: 0.001Ω
• Damping factor: 8000
• Bandwidth: DC-30kHz @ -0.1dB, DC-95kHz @ -3dB
• Phase Rotation: 0.2° at 20kHz, 0.9° at 40kHz
• Thermal Distortion: Below measurement threshold

Those are incredible by any standard.  The fact that the DAC and phono section are encased in the same unit, with the shortest signal path in the industry only helps to maintain superb performance.  This is not a lifestyle product when it comes to performance.  It easily challenges any system at any price point. 

Using a Chord M-Scaler as a front end processor for the digital streams.  As good as the Devialet is, the M-Scaler provides further improvement with digital playback.  Helps get transients and time domain in order.

The key to obtaining this level of performance is the Analog/Digital Hybrid (ADH) amp system.  It combines two different amp setups: A class A analog amp section for voltage control, and a Class D amp for current control.  No other amp of any class is like this, it's a truly unique design. 

Will post observations after some extended listening, but so far, so good.  This has the reserve power to handle dynamic contrasts from symphonic music, which to me, is the acid test for a audio setup.

https://soundstageultra.com/index.php/equipment-menu/687-devialet-expert-1000-pro-mono-dac-integrated-amplifiers

[Freo-1]

Sorry, had to edit due to browser issues   

[mresseguie]

Gee. With only 1000w/ch, you might have a difficult time driving your speakers. [I'm joking!]

Congratulations on finding this amp. I'm guessing it didn't just happen to pop up on your local Craig's List.

Michael

[Freo-1]

Nope. Happened to get an alert on hifishark.com 


Just wanted to get out the word that Devialet amps are a viable option for high end audio.  Highly recommended for audition.

[Freo-1]

Well, after some extended listening, can report that the Expert Pro 1000 is an amazing bit of kit.  Long ago, when I first jumped into the high end pool, had a pair of Carver M-1.0 T connected to a pair of Acoustat Spectra 33's.  Those were in mono, so they could output 1000 watts.  The Acoustasts could easily absorb all that power. 

Since then, went though a lot of gear, but nothing ever approaching 1000 watts again.  The highest power amps since then were the Devialet D-Premier mono setup, which was 500 watts.  There is something special about having high power amps in ones playback setup.   It's most noticeable with reproducing non amplified instruments, and to some extent with vocals.  If one listens primarily to rock/pop, the high power amps will less of an impact on sound reproduction then with a full scale symphony orchestra. 

These are definitely still at the cutting edge of what modern technology is capable of.  Being able to get 1000 watts out of the unit of this size is a feat, but the sound from these is among the best obtainable is a coup de grace.  Listening to the Berlin Philharmonic 25 year anniversary, the increase in dynamics and clarity almost made you feel like you were there.  Every aspect of playback took on a significant improvement.  The loud passages in a given movement no longer sounded compressed at all.  Some recordings that I thought were compressed turned out not to be so.  Instead, what I think happens is the transients are clipping, which causes the brief congested sounds. 

Found this white paper which may explain what goes on.  I'm coming around to the thinking that even though the average playback wattage is small, in order to reproduce transients without clipping on music with high dynamic contrasts, the amp NEEDS a LOT of reserve power to achieve this.  Tubes soft clipping masks this behavior to some extent.

https://sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors

[Freo-1]

I think these statements from the Sanders white paper gets to the heart of the matter:


" In short, my take on amplifiers is to use a tube amp that clips gracefully if I must listen to a clipping amp.  But I'd rather have an amplifier with so much power that it never clips!  The sound from powerful amps is dramatically better than underpowered amps, even if they clip nicely."

Now, combine that with this statement:

You will find that conventional, direct-radiator (not horn-loaded), magnetic speaker systems of around 90 dB sensitivity, require around 500 watts/channel to avoid clipping.  More power is needed in larger rooms or if you like to play your music more loudly than most."

More from the Sanders White Paper:
" The key point I'm trying to make is that audiophiles usually are using underpowered amplifiers and are therefore listening to clipping amplifiers most of the time. When an amplifier is clipping, it is behaving (and sounding) grossly differently than its measured performance would suggest. This is because we always measure amplifiers when they are operating within their design parameters -- never when clipping.  A clipping amp has horrible performance, so attempting to measure it is a waste of time.  In other words, we usually listen to an amplifier when it is clipping and we measure it when it is not. This is why amplifiers sound so different than their measurements would imply. It is not that measurements are wrong, it is simply that we are listening and measuring different conditions.  It is essential to understand that when an amp is clipping, it will sound quite different than when it is not clipping. It is also important to realize that different types of output devices (tubes vs. transistors) clip in very different ways, so sound quite different when they are clipping.
Finally, it is important to realize that an amp does not instantly recover from clipping. It takes several milliseconds for its power supply voltage to recover, for it to recharge its power supply capacitors, and for its internal circuitry to settle down and operate properly again. Therefore, even though an amp may only be clipping on the musical peaks, it will not immediately operate properly at average music levels where it is not clipping."



Based on the above, this is why I think the Expert Pro 1000 sounds so good. 

[Freo-1]

Here is an explanation of the difference between Class D and Devialet ADH from hifinews.uk:

" All Devialet's ADH amplifiers represent a unique twist on Quad's 'feedforward' Class A/B Current Dumping technique, first applied in its 405 power amp over 40 years ago [Wireless World, Dec '75].
In this new-age implementation, a very high quality analogue Class A (voltage) amplifier is directly coupled to the speaker while a digital Class D stage provides the current to maintain this voltage across
the speaker load. Hence the term 'ADH' or 'Analogue/Digital Hybrid'.
In practice the Class A preamp is a transconductance stage that converts the current output of the amplifier's PCM1792 DACs into a voltage. By keeping all its processing in the digital domain until the final output, Devialet has engineered an analogue stage with a minuscule signal path. It calls this its 'Magic Wire'. It's this Class A voltage preamp - not the rugged Class D dumpers - that defines the quality and performance of the amplifier as a whole, and this includes the filtering of its switched PWM output. So, unlike conventional Class D amps, the Original d'Atelier (Expert Pro) is free of an invasive LC filter network just ahead of its speaker outputs and its performance remains unaffected by speaker load impedance. "

[I.Greyhound Fan]

I would love to hear one of these amps.  All I have read are good things.  I almost bought a used amp as I am eventually going to move on from my 100lb Pass Amp and 50 BAT tube preamp that is a space heater with its tubes.

[Freo-1]

I would love to hear one of these amps.  All I have read are good things.  I almost bought a used amp as I am eventually going to move on from my 100lb Pass Amp and 50 BAT tube preamp that is a space heater with its tubes.

As a big supporter  of all things by Nelson Pass, I can report that the sound reproduction from the Expert 1000 Pro is (subjectively) at whole different level.  When I first auditioned Devialet in 2017, did not want to believe it would be as good as my various Pass amps and preamps.  Well, I was wrong.  Wound up selling all my Pass gear for a Expert 400. 


Since then, migrated to D-Premiers in mono, then a Expert Pro 220 (which I have as a second system).  Upgraded one of the D-Premier units to an Expert Pro 250, and was gob smacked at the improvement.  When I got the Expert Pro 250 back, decided to use the Chord M-Scaler from the headphone setup to evaluate to the 250 Pro.  That took the sound to a higher level still.  Transients and Time Domain was greatly improved. 


When the opportunity arose to get the second 250 Pro at a great price, jumped on it.  I had dual mono before, and the improvement was subtle, but noticeable.  However, the 1000 Pro was WAY better than the previous Devialet dual mono setups I had.  That's when I stumbled onto the Sanders white paper about tubes/transistors, and clipping. 


This setup has convinced me that his statement about a 90 db speaker requiring 500 watts to avoid clipping is accurate.  Unit I heard this setup for myself, would not have believed it, and argued against it.  No more. 


Besides, it's nice to have a couple of twenty some odd pound units vs. 100 lb behemoths.   
Don't need to spend $$$ on interconnects either.   

[mav52]

I heard these at a show, but way the hell out of my budget.  Enjoy.

[kmmd]

Besides, it's nice to have a couple of twenty some odd pound units vs. 100 lb behemoths.   
Don't need to spend $$$ on interconnects either.

Congrats on the Expert Pro 1000.  These are products that I hope to audition.  They highlight a short signal path which I agree with.  As you mentioned, you save on ICs and also PCs.  It’s quite interesting that they use the BB 1792 DAC and not newer generation ones.  The 1792s have always been extremely musical.  It’s all about the implementation and the surrounding components and stages.

Someday I’ll move on from my separates.  Heck I have boxed speakers as my mains from decades of using Maggies.  I’ve enjoyed my 100 lb Pass Labs X250.8, but I have another amp coming in less than 2 weeks.  It’s 110 lbs and is Class A to 100 watts - Coda No. 16.  It also doesn’t run hot.  After reading several threads about it, including Ted B’s input on the What’s Best thread, I pulled the trigger.  Just don’t tell my wife that she’ll help me move the X250.8 and Coda.  Then don’t tell her that my ultimate goal is to move the Pass Labs amp upstairs to power my bedroom system. Lol

Enjoy and happy listening!

[Freo-1]

Congrats on the Expert Pro 1000.  These are products that I hope to audition.  They highlight a short signal path which I agree with.  As you mentioned, you save on ICs and also PCs.  It’s quite interesting that they use the BB 1792 DAC and not newer generation ones.  The 1792s have always been extremely musical.  It’s all about the implementation and the surrounding components and stages.

Someday I’ll move on from my separates.  Heck I have boxed speakers as my mains from decades of using Maggies.  I’ve enjoyed my 100 lb Pass Labs X250.8, but I have another amp coming in less than 2 weeks.  It’s 110 lbs and is Class A to 100 watts - Coda No. 16.  It also doesn’t run hot.  After reading several threads about it, including Ted B’s input on the What’s Best thread, I pulled the trigger.  Just don’t tell my wife that she’ll help me move the X250.8 and Coda.  Then don’t tell her that my ultimate goal is to move the Pass Labs amp upstairs to power my bedroom system. Lol

Enjoy and happy listening!

Thank you.   I've always have had a soft spot for Pass Labs and Coda gear.  Enjoy, and be careful not to wrench your back!