Impedance Mismatch ???

Well Thank you Gentlemen for the quick reply and the analogy of the drumhead being struck helps nicely !
From now on, the impedance rating will be part of any amp and preamp that I might ventue on to.
Actually been looking around for a little while now and that`s how I stumbled across this subject !
Thanks again guys !

Strangely, Jeff Rowland increased ICEpower module input impedance from 10k to 40k by adding extra amplifier board on my model 102 amplifier but released brand new all his design model 625 that has only 10k input impedance. Does he know something we don't?

Adding an extra stage to increase input impedance to 40k probably degrades sound a little bit, so not doing so would be an improvement. The trade off is less compatibility with tube linestages which can have fairly high output impedances. Rowland may have decided that the tradeoff is worthwhile, either because of the performance gain and/or because tube linestages are unlikely to be used with that particular amp.

Could be.

I would probably not be concerned with most any amp input impedance 10K or higher for use with SS mainly. Use of higher output impedance tube pre-amps is the scenario that is more problematic. Tube pre-amps are popular with audiophiles these days but are probably still a very niche market overall. Many amps including stock Icepower have only 10K input impedance. That may just be the most practical approach with the most appeal.

I love the sound of my ARC tube pre but I am sure there are similarly good sounding SS pre-amps out there for reasonable cost as well. My next pre-amp I buy and keep someday will likely be SS as long as it is not a step backwards from teh ARC.

I say that because even my 30+ year old SS NAD 7020 receiver that I am using in my family room system today as a pre-amp only with the TAD Hibachi amps and OHM 100S3 speakers sounds very good, although it is guilty of a touch of that warmer sound that NAD can be known for. Its' my long time spare unit that I put it in to replace my similar older Carver pre-amp in that system when the Carver developed a problem needing repair. I would like to try a newer good quality SS pre-amp in there sometime soon when I can come up with a good justification at which time I might try a shootout for my ARC pre-amps place in my main system.

Larryi, that might be the case but when he designs whole amp (instead of using Icepower modules) most likely he has option of setting 10k or 40k input impedance without extra stage. It might be electrical noise issue since higher impedance input is more likely to pickup interference. Preamp side is low output impedance, but not at the radio frequencies where it might be tens of kiloohms. It is tradeoff between performance of the best amp and convenience of matching for lower end amps. It is feasible that, as you suggested, he targeted class D amps for use with tube preamps while his new model 625 is class AB.