Need help What monoblock power amps for bass?

Don't use a pot. I've tried a few in this situation and they just sounded ugly. Constant twiddling and never found the right setting. The really good audio pots are not the right range for this type of fine tuning. A series stereo attenuator in the 0-5k range should work for most combos. However, you could always just add another series resistor to a smaller range attenuator. Of course, this works a lot easier for RCA connections. XLR balanced means doubling up on everything. Series attenuators work well in this situation because they only raise impedance that was already compromised by parallel amps.

This kind of biamping, with different amps only tends to work well when the xover point is low, 150Hz or less.

If you want monoblocks with the convenience of a SINGLE chassis, I would consider a used Parasound HCA-3500 power amp.
The unit is fully dual-mono, has lots and lots of power and current, and even has seperate power cords for each channel!
This amp has Krell or Bryston-like bass control and power!
Look up the review of this amp in the Stereophile archives.
It talks about the bass capabilities of this amp, etc.
Highly recommended.

Thanks a lot for all your kind answers.Dalton,monoblocks are mandatory due to the short speakers cables i own.I already chose this setup along time ago.

Ngjockey,i am still considering what attenuator to use,still i am not clear on this.Your input is very helpfull.But you were right,i was considering the pots.

Ramy,your speakers seems very serious and good.I appreciatte the input.I think power is not very important for Sinfonias,anything above 50 Watt would be ok.

Audiobb, my experience has been that while you can get much greater volume levels by bi-amplifying, you also pay a big price- figuratively and literally! First, to do it right you have to use and electronic crossover. Good ones are expensive, and all of them behave not only as crossovers but also as filters for detail and impact. You also have to pay for another amplifier.

I have found the most convincing systems don't use electronic crossovers, instead the amplifier drives the speaker full-range. Otherwise you face prodigious integration issues, and the better your speaker is the more you will notice them. For example, its a lot easier to bi-amplify if you use the same type of amplifier for top and bottom, as far as integration is concerned. That could be tricky in your case where you have an SET on top.

At any rate I've never seen a bi-amplified system work right. I've seen them sound OK, and I am open to the idea that one day I'll hear one that is done right but until then I advise against it- if best possible sound quality is your goal.

Ralph, regarding your comments on bi-amplified systems, have you ever heard
the Orion system designed by Sig Linkwitz? In its intended configuration a
separate amplifier channel is used for each of the four drivers per speaker
channel. This is with an electronic crossover.

The Orion system has a very large internet following and reading Mr. Linkwitz's
site I found his design objectives closely match my listening goals. However,
I've heard two different Orion systems and was disappointed in both. I expected
the individual amp/driver configuration would have been an advantage (low
distortion?). Now, from your comments, I wonder if this could have been a
detriment?