I think I've made up my mind

Tvad,

I think I recall you indicating in prior discussions that you believe higher amp input impedance generally leads to directly observable improved bass performance, or something to that effect, which technically sounds viable to me.

In that case, 30K ohms is a lot closer to the low end for SS amps I have seen (about 10K ohms) than it is the max I have seen (about 200K ohm balanced).

It would be more of a factor for higher output impedance tube pre-amps than lower impedance SS pre-amps.

"Nevertheless, if you have specific numbers that would suggest a non-optimal match, then I'd be interested in seeing them and learning more."

No.

I'm only suggesting (as unless I'm mistaken I recall you have suggested to others as well in past threads) that if what you heard was not good, and a tube pre-amp was used, an amp with 60K, 100K, or 200K input impedance would probably sound different and might sound better than one with 30K input impedance, all other factors aside.

Tvad,

Understood.

My recent move from an amp with 62K input impedance (Musical Fidelity A3CR) to one with a 100K input impedance (BC ref1000mkii) produced a difference in sound of the type and magnitude that would seem to support this theory and the physics behind the theory makes sense to me.


That's not to say that such a change in a single spec assures better sound, but the effects may be somewhat predictable in the case of impedance matching when heard I believe, which is of benefit.

The change in sound in my case was a marginal but noticeable improvement in overall clarity, dynamics and detail. That is pretty much what I was looking for in going to a SS amp (class D in this case) with higher than average input impedance specs that appeared to be a safer if not necessarily better match with a tube pre-amp.

Whether the resulting sound is better or not is always a matter of taste and preference and other technical factors as well. Specs are a guideline to better sound perhaps in some cases (like impedance matching) but only tell part of the story.

I think one of Bel canto's rationals for the design of the mkii version of the Ref 1000s was to help assure an optimal match with more pre-amps, tube pre-amps in particular. The input impedance was raised from standard IcePower 10K input impedance in the original ref1000s to 100K (unbalanced)in the newer mkii versions, which is largely why I sprung for the much more expensive mkiis over the originals, to help assure optimal results with the ARC sp16 pre-amp in my system.