Recommended Preamp for pairing an Adcom 555II Amp and Theil CS 3.5 speakers


My Bryston 0.5B preamp was inadvertently put down over the holidays by an incident now known as 'The Sippy Cup Mystery'.  Regardless of the cause, I need a new preamp for my system.  I am driving a pair of Thiel CS 3.5  (with the electronic bass equalizer) speakers with an Adcom GFA-555II amp.  The majority of the eclectic music (classical, 80s, folk, funk) being played on the system is streamed from iTunes through my Audioengine B1 DAC.  I have read a number of posts with various recommendations for the GFA-555II or the Thiel CS 3.5s but not for their paring.  Short of winning the lottery this week, cost is a factor. Any suggestions or directions would be very much appreciated.
iowanna33
I have used the GFA 555 with the GFP 565 and while the pair is very good sounding (and the 565 has a great phono section if your into vinyl). But, I will say that when I installed the Modwright SWL 9.0 SE ($1000 used) it really showed me how beautiful sounding the Adcom 555 can be. A tubed pre amp is what I highly recommend. Manley labs shrimp?? possibly. Doge 8 Clarity, Dehavilland Ultraverve III, these are all tube based and around your price range and are very special indeed. Also, all of these will have very low output impedance to drive the Adcom no problem.


Matt M
iowanna33
Recommended Preamp for pairing an Adcom 555II Amp and Theil CS 3.5 speakers

Your Audio Engine B1 has
Analog Output: 2V Max.
Analog Output Impedance: 57 Ohms.

And your Adcom 555II as was pointed out has:
100kohm input impdance
only needs 1.75v in for full 200w output

As you can see the 2v from your B1 is more than enough to run the 555 to full output, so you don’t need an active preamp with gain that you don't need.
Also the output impedance of the B1 is 57ohms and this is a great match for a passive preamp, which will aslo match prefectly with the 555’s 100kohm input impedance.

Get one of these and save a fortune, you’ll have the most transparent/dynamic sound and save a fortune on not needing a fancy/expensive preamp that will colour the sound in comparison.

$49 http://www.schiit.com/products/sys passive only

$349 http://www.schiit.com/products/saga if you want to switch from passive to tube output as well .

$699 http://www.schiit.com/products/freya if to want to switch from passive to solid state or tube output.

In all three I think with your setup the passive will win out, so for $49 go the first one.

Cheers George

While george is right about the specs on paper, the actual outcome is a different story. I have tried the $49 Schiit Sys between my CD player and 555 and the sound quality was completely lifeless and flat as compared with my Adcom preamp and nowhere near the sound quality when I experimented with the tube preamp in there. The volume control on the Sys is also marginal at best. But it's definitely worth the $49 price when used as an input selector.

What's the budget?

@kalali  You beat me to it!  I was going to respond to George much as you did above that my anecdotal understanding of passive units is that the PRAT as the Brits like to call it, is diminished.  I'm not making a categorical statement here, just that anecdotally over many years reading lots of audiophiles' experiences, that the drive is diminished by passive gear.
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