[abernardi]

  I'm not sure whether to post this in the Apple section or here, it covers both.  Up until last week I was using an external USB HD going to an iMac running the Logitech media server, going wirelessly to a Squeezebox Touch with a good linear power supply, coax S/PDIF to an Audio-gd NFB-2 DAC to a battery powered Virtue Sensation integrated tripath amp w/Dodd tube buffer. 

  Last week I switched over to a Mac Mini with a Mapleshade (modified M2Tech Hiface) USB-S/PDIF interface directly into the DAC and I am not yet happy at all with the sound.  The naturalness seems to have disappeared, the bass is fatter, not in a good way, and the signal to my amp is much hotter.
 
  There's also a weird dynamic thing going on that makes me want to turn up the volume to uncomfortable levels in order to hear everything.  There's a constriction, it's like the dynamic range has noticeably gotten worse so in order to hear the detail I heard before particularly in the upper mid range I have to crank up the volume.  It reminds me of bad dolby B decoding on a cassette deck, does that make sense?  Also the attacks are smoother (slower?), initially pleasing, but not quite natural.

  I read a few posts on head-fi.org in their NFB-2 thread about problems with the hiface interface because it has a higher output voltage than normal and some people report that the NFB can't handle it at all.

  So far I've focused on the Mac.  I dumped iTunes and went to Pure Music and made the settings adjustments they recommend and loading the media into RAM.  It definitely got better, but still not great.  So far I've just been listening to a 24/88.2 SACD rip.  The Hiface can go up to 192K, but the NFB-2 maxes out at 96K, so upsampling would probably be a bad idea.

  Right now I'm suspecting the power to the Mac.  I'm using the supplied power cord (it has an internal power supply) and it's plugged into an old Monster surge/conditioner strip and I'm wondering if that's causing the congestion.  So I'll take that out of the system today and see what happens.  Also, if that hiface is putting out too hot a signal, I could see that causing the problem.

  I also moved my whole rig to a different location, different rack, so that could change things.  I know, too many changes at once.  I also might try putting the SB back in the system with the Mac Mini and see how that sounds, but I'd rather use the Mac interface than the SB interface.

  Any ideas?

[srb]

One more thing to try as a test would be to connect the Mac Mini's optical audio output to the DAC, taking the HiFace converter out of the equation.  If that sounds better, you could see about auditioning a different USB to S/PDIF converter, or maybe you'll be satisified with the optical and its 24/96 limit.

Steve

[avta]

Agree with Steve's suggestion. If you have some headphones you could plug them into the Touch and see if that sound is more of what you expect. That would bypass your dac, converter and amp. That would let you see if the computer and/or Touch is the problem.

[JLM]

Confused (Weird dynamics)...

Increased dynamics (a sign of better fidelity) does require you to turn up the volume to hear the lowest passages (hence the need for quieter listening environment and/or listening at higher volume to hear it all).  So what's the compliant?

Confused (dumped iTunes for Pure Music)...

I thought Pure Music was a supplemental program to iTunes.   

[abernardi]

JLM,
  I know exactly what your saying and that confused me too as I was trying to explain it.  But it isn't simply dynamic range, it's more like noise suppression, like a limiter, actually, very much like a limiter, when the sound level gets down to a certain point, the level dips substantially.  I thought at first it was better dynamic range and I just wasn't used to it, but I've heard these cuts on systems much better than mine and I know what it should sound like, and this isn't it. 

  Pure Music uses iTunes just as a front end to access the database, but that's all iTunes is doing.  Sonically, it's out of the loop.

[Blackmore]

Can you double check your volume setting in Pure Music? (left side of the PM window). I've had poor results if it wasn't set to "0" for my DAC. 

[avta]

and check the volume of the Touch. It's best set at 100% in my experience.

[abernardi]

  I put the SB back in the system and noticed right away that the decay was indeed longer and had more shimmer than the Mac Mini.  But I also noticed the sibilance was harsher, more distortion.  When I went back to the Mac Mini, the harshness went away and I noticed more detail and tighter bass.
 
  I think one thing that's happened is now that the source is improved, it's showing the weaknesses in the rest of the system.  I know there should be more decay, but I think I was getting that decay from the SB at a price - distortion.  The Mac Mini is much cleaner up there.

  I'm not sure why I thought it was less natural sounding, but I think it's because I got used to the SB sound and the more accurate source took away some of that artificial "space" and shimmer coming from the SB. 

  Man, I gotta lay off the sharpen tool, it's seductive.  I don't really know what I'm talking about, but that's what this layman's mind is coming up with.

[jrebman]

abernardi,

Yes, lots of variables here, including break-in time.  Yes, the stock power cable that comes with the mini is absolute ccrap for music purposes, and the quality of spdif cable can be pretty significant with the mapleshade converter -- try one of the mapleshade spdif cables if you can -- they're weird, but pretty damned amazing.  I don't have the nfb-2 anymore and never had any problem with the coax input myself, but that might be something to consider when the poer cable to the mac and spdif cables are dealt with.

I'm assuming that your Touch has no modifications, is that correct?

Also, if you want to try, mapleshade also makes their power cables with a C7 connector -- and of course there's a 30-day trial.  Yes, I know sometimes it's hard to wrap one's head around some of their designs, but I have yet to be let down by any of their claims.

Good luck and hope this helps,

Jim

[abernardi]

Thanks Jim,  I'll look into it.  The touch just has a an upgraded power supply.  Things are sounding a bit better with time.  My spdif cable is an Auricle Audio Encore! Signature I bought off someone here.  It has pretty good reviews but I have not compared it to any others.

[JLM]

Try to osolate one variable at a time. 

Regarding power abberations, try listening late night.

[jrebman]

Ok, thenit should be  an easily discernable upgrade in sound from the Mac.

I don't know the particular spdif cable you are using, but it doesn't ring any bells as one that may be an issue.  Also, are you running headless and using a virtual console or iDevice to control the system, or can you give that a try if you're not?  That will also likely take things up several notches (the monitor is another big source of noise pollution).  And finally, if you can't get rid of the monitor and have a 2011 mini, you can try a good glass toslink cable from Lifatech into the dac as that will at least provide some measure of galvanic isolation between the mini and dac (though poor power and the monitor will still effect the internal signal processing in the mini somewhat.  In digital and computer music, clean power is probably the biggest issue to deal with -- it effects everything.  BTW, the reason for toslink on the 2011 is that the 2011 minis have a substantially better toslink transmitter in them than the previous minis, as well as all other previous macs.  It's a new generation of toslink chips and will hopefully be making it's way into other products from here on out.  Who knows, maybe we'll even see a 24/192 toslink transmitter in the 2012 mac mini -- they're certainly available and out there now (the chips, that is.)

Good luck and if you need any more assistance, ping me offline and I'll do what I can to help.

-- Jim

[abernardi]

  Jim, I am running it headless and have been controlling it with screen share on the imac and also from an ipad.  I'll have to pick up a toslink cable and try that out.

  I did some more critical listening tonight and my ears are zeroing in on some things.  First I'm realizing I changed too many things at once, , and I need to roll it back to the original setup, and take one thing at a time.

  Currently the positives are that the detail is much better.  The toe-tap factor has increased.  Less harshness/ring/distortion/sibilance in the highs.  The low end is more detailed, but not as lush.  The negatives are this limiting/constriction and less natural impression. 
 
    I failed to mention I've been playing with a couple of sets of speakers as well, my great old Tannoy PBM-5's (don't laugh, they're way better than they should be), and a pair of Hornshoppe Horns with a 4" Fostex driver.  Two radically different approaches.  I think my limiting problem is coming from how the Sensation amp and the horns are interacting.  I don't know what the resistance numbers are on these, but I'd bet something's going on there.  Initially I didn't think that could be an issue because the horns are more sensitive and need less juice, yet they need to be pushed harder to hear everything and it's fatiguing on the ears.  I love their pinpoint imaging, it's unreal, but I find myself tensing up as I listen to these speakers.
   In comparison, the Tannoys are like taking the water flow restrictor out of the faucet.  Anyway, it's pointless to try to figure this out until I do more reasonable testing.  Thanks all.