Why do some fine solid state amplifiers like Soulution have such low input impedance?


I was looking at an excellent deal on a 5 series Soulution stereo amplifier to mate with my VAC Renaissance 5 preamplifier.  I then found out that the Soulution has an input impedance of 2000 Ohms balanced. Although my VAC is transformer coupled at the output, I am going to pass on the Soulution. Each component is too good alone to worry about a compromised “marriage”.  Do SS amplifier manufacturers find sonic benefit in such low input impedances, or is it really to discourage use with tube preamplifiers and encourage sales of their own preamplifiers?   
audiobrian

Showing 1 response by soix

I noticed that at least some SMcAudio-revised McCormack amps have much lower input impedance compared to the stock models. I don’t know what specifically Steve does in the revisions that produces this, but given the results he clearly feels it’s a worthwhile tradeoff for improved sonics. But given Steve’s practical nature and Kirkus’s point about limiting the sonic benefit for 95% of audiophiles to accommodate a few outliers, the choice for a lower input impedance seems like pretty reasonable one in the scheme of things. No?

As a stupid follow-up question, does increasing the bias in a SS amp have an effect on input impedance? Or, put another way, could you increase the operating bias in an amp without raising the input impedance, and if you did that what would be the sonic trade offs?  Of course there are Class-A amps that seem to have reasonably low input impedances, so maybe I answered my own question.  Yes I know, I’m a moron.