[Lindahl]

I haven't read a lot just yet on passive preamps, just starting to understand the basics. I'm trying to keep my setup very simple (even if it requires the complexities of DIY gear), and it looks like my gear is suitable for a passive preamp setup, and just want to do a sanity check with those who know *MUCH* more than I do.

Onkyo CX390 CD changer
2V RMS output voltage
470 ohm output impedance

Sonos ZP80
2V RMS output voltage
90 ohm output impedance

Emotiva RPA-1
200w/ch into 8, 300w/ch into 4
27dB gain
200 damping factor (8 ohms)
input impedance 47k ohm
input sensitivity 1.75V RMS

Monitor Audio RS6's
91dB sensitivity
6 ohms

I was planning on just getting Endler's Twentyfour Step PassivePre, which would handle input selection and attenuation. Does this all look like a good match for a passive preamp setup? After reading around on his website, he talks about how great the Behringer SRC2496 is, as a DAC - I could use the Toslink and RCA inputs on it, and skip a the PassivePre, and just get two shotgun attenuators, hooked up directly to the amplifier. What do the experts think? Any suggestions?


EDIT: Emotiva's datasheet was wrong. The amp requires 1.75V for full gain at 27db (not 1V for full gain at 29db). 1.75 is getting up there, and is pretty close to 2V, or am I still good?

[rollo]

The transformer based TVCs are all the rage at the moment. Promitheus Audio TVC is leading the pack in sonics and price. The Music First is $2700US and IMO is not 8x better than the Promitheus. In fact they are equal at best. We have conducted numerous listening sessions comparing both with no winner per say. Just a little different presentation. The S&B unit may have a tad more depth to the soundstage but that is IMO. The S&B trannies are no longer available for DIY projects anyway.
   So what are you waiting for. Your CDP has the desireable output voltage. If your amp has a low input sensitivity you are in like Flynn.

    rollo

[konut]

All the numbers look good.  The SRC has a pretty hot pro level output.
http://www.behringerdownload.de/SRC2496/SRC2496_SPECS_Rev_E.pdf
You might need the Endlers after it. The Behringer DCX Xover has the same problem. Some have modded these to eliminate the opamp outputs running direct from the DAC chip. Others have used attenuators like the Endlers.

[John Casler]

The whole world is a purple knif!

Ernie Anderson? (AKA Ghoulardi)???

[konut]

The whole world is a purple knif!

Ernie Anderson? (AKA Ghoulardi)???

Correct!! And remember, Ghoulardi LOOOVES you!   

[Lindahl]

Rollo, do you know how much voltage loss there is in the Promitheus TVC at unity gain? Or is it strictly unity gain? Since I have 2 volt sources and my amp is 1.75 volts to drive to full amplification, I'm cutting it a bit close. Though... the amp does have 200 watts per channel, and the speakers are 91dB. Though, I'm not exactly in a huge room so I'd probably be insane to want those kinds of peaks - 115dbs - for music, at least.