Jeff Rowlands Amp and Dac vs. VAC amp and DAC

Hi Richard, I freely admit that the UI for volume attenuation/gain on Aeris is a little, ahem.... Techno-terse.

I would have prefered an LED with attenuation values, in addition to an independent indicator that would light up when the unity value optimum for direct use into amps is reached.... E.g. same solid LED, but with label "Direct".

In general, you will find the Aeris manual to be a pretty good source of operational info on the device. Volume control for direct use into amps is discussed on page 16.

Delighted that with Aeris at 0dB attenuation, your M625 S2 delivers all the juice you need for your hungry speakers!

Saluti, Guido

Ricred1 5-23-2016 9:14pm EDT
I was originally told to set the attenuation on the DAC so that the left and right volume LED’s are of equal brightness.

It could be that that setting would be appropriate for use with a preamp providing significantly higher gain than whatever gain your Corus may be set to. (The gain of the Corus is indicated as being "Independently Programmable 0 to 20 dB on each input").

I would guess that part of the rationale for the adjustment Guido and Mr. Rowland pointed you to might be that it would minimize possible sonic side-effects of the DAC’s volume control mechanism. Such as what is referred to as "bit stripping," if the volume control function is implemented digitally.

In any event, glad that the issue is resolved. As I mentioned earlier it would seem, on paper at least, that your 625 S2 can provide much more power than would ever be used with your speakers.

BTW, Guido, I think you may have inadvertently misworded the second paragraph of your post just above. I believe the reference to unity value should be for use with a preamp, not "for direct use into amps."

Best regards,
-- Al

Again, a lot of good information is arising in this thread. To answer the question about what other speakers I auditioned -- I didn't. I had no intention of even purchasing speakers. I went to a Sabrina audition with Peter McGrath and lo and behold I was hooked. At the time it was used with MacIntosh equipment (not my favourite) but they sounded just great. I loved everything about them. The were refined, warm and yet alive all at the same time. I love the cabinet (also important to me). And by selling my older equipment I could afford them. I haven't listened to anything else. I think they are perfect. I just want to pair them with a good amp and be happy listening!! 

Al, the Aeris volume control is neither purely digital nor purely analog. Per the Rowland knowledge base, it operates by varying the reference voltage in the DAC chip. See:

http://jeffrowlandgroup.com/kb/questions.php?questionid=617

There is a variety of other technical information on the Aeris DAC in the Rowland knowledge base:

http://jeffrowlandgroup.com/kb/categories.php?categoryid=205

Regards, G.

Oops... You are right Al... 0 attenuation / unity gain is for DAC feeding a preamp... I Must be getting old! G.