Are Pre-Amps necessary?

https://soundcloud.com/johnhdarko/whats-the-deal-with-pre-amplifiers

From Vinnie Rossi  
Podcast

mitch2
I have owned a DAC with a passive VC, but do not remember seeing one with an active stage.

That’s because most dac’s with VC’s do it in the digital domain, yours was a rare one to have a passive VC on it’s output inside the dac, and that would have had to have been after an active buffer anyway, as if not, then it would have had to be after the I/V (current to voltage converter stage) and that would not have been a good idea..

I am surprised manufacturers of those DACs with VC don’t provide a unity gain buffered output.

The ones that have VC’s in the digital domain, all have active output buffers, unity or with gain, as did yours, but it was before the passive VC on the output, what brand model was it??

Cheers George

George, it was the Metrum Acoustics Adagio, which  changes the volume by controlling/changing the reference voltage to adjust the output voltage of the DAC.

mitch2

Interesting, it has to quote:

"The clever implementation of the volume control by lowering or raising the reference voltage "in the converters" is something I have never seen before and works flawlessly."
" And, its volume control is neither conventional analog nor lossy digital."

This to me means you would definitely have an I/V (current to voltage converter) stage after the R2R dac chip set, and then also an output buffer with or without gain.
It’s output impedance is <100ohms SE at 2v output, which means it has an output buffer, and is a great candidate for direct to amp connection, and no problem with your SMc monos 10kohm input impedance, they only need 1v in, for full peak wattage output

So Mitch, get rid of all those preamps you have

• Hattor Audio Mini Passive-Active Pre with Takman REY, XLR, and opamp active buffer ($1,550)
• Benchmark LA4 ($2,599)
• W4S STP-SE ( $1,999)
• Schiit Freya ($850)
• Tortuga Audio with CuTf caps ($4,019)
• SPL Volume 2 ($499 - considered but ruled out because no remote volume)

Because you "should" blow all of them away, with what you have above, by going direct.

Cheers George