Monoblocks did not work

Indeed that's strange! Is it something in the architecture? The following link treats bi-amping -- but may be helpful nevertheless: http://www.sound.au.com/bi-amp.htm

I'm sure there is a very simple solution to great sound.
Good luck!

How are you running these amps ? Bi-amped ( vertical or horizontal ) or bridged ??? From the input that you've stated about power output per channel, i'm assuming bridged.

For sake of clarity and those that may not know the different terms, vertical biamping uses one stereo amp per speaker. Channel A runs the bass section of the speaker and channel B runs the mids and highs.

Horizontal uses one channel of each amp for the bass and the two channels of the other amp feed the highs.

Bridging takes the two channels of a stereo amp and converts them into one BIG channel. You then need two amps in order to make a stereo pair.

All three of these arrangements sound different even though your using two identical amps. Bridging typically gives the highest voltage levels possible out of the three different arrangements but usually results in a much harder and thinner sound. Sean
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Sean and Snook2 I bridged each amp to form one big channel. Amps are bridgable. Gregm thaks for the tip, I will be sure to look it up. I should mention that, Classe did recommend Vertical biamp than the monoblocks. But need, Two sets of interconnects (same brand) with Y-splitter at the pre-amp. I bought extra pair of speaker cables same length, same brand. IC would be tricky, since I have to deal with y-splitter. Probably would inquire with the Straightwire tommorow. But I don't want spend extra $500-600 with same results, without proper feedback from Agoners. Thx.
p.s. Let me tell you that my current sound using only one CA-400 is GREAT, but sound stage depth improvement is desired-without moving the speakers!!

Nilthepill. I am no techo, but I think bridging ups the wattage but makes the speaker load look twice as difficult. So maybe the sound you are getting is what the Classe would sound like into a 2ohm load - could be, and no doubt someone will correct me if I am wrong - please be gentle?

I would be very tempted to peek inside the Classe and see if I could link together the hot connections on the left and right input RCAs without doing any real damage (or get someone competent to do it for you - possibly a better result than using Y connectors, and a darn sight cheaper than buying additional interconnects.

I don't know if your CA400s are also balanced or not, but I recently vertical bi-amped a pair of McCormack amps using RCA ICs, and I accidently switched one amp to the balanced mode and got sound like you describe.

Do the CA400s have balanced switching of some kind? Other than that, I would make sure all speaker cables are attached to the correct speaker and amp terminals for the way the monos need to work. Good Luck. Craig