i just purchased a pair of polk lsi9's and have a velodyne 150w sub. currently i am using an old pioneer 2ch amp. since the amp has proven inadequate it is time to upgrade. i'd like to take advantage of the lsi9's biamp capability. is there an amp that has 5ch or a 4ch with sub output? it's probably obvious that i'm trying to "biamp" with a single unit or rather a single volume knob. the ONLY input source is a cd player and occasionally my daughter's ipod. it appears that a 5.1 receiver won't do since the power output to the various channels varies. unless of course there's a 5.1 that delivers the same power to all the channels. my minimum requirements are an amp with a single input, a power switch, volume knob and output in the 100-200w range. anything over and above would just get ignored. "old school" or maybe just old is the reason for what may be a silly question. if buying two amps is the only way to get where i'm going then i may seek advice on how to explain that there are now TWO volume knobs. any and all advice and suggestions welcome.
First off, I do not know of any big multichannel amps with a subwoofer output. You need an AVR or a preamp/processor coupled to a multichannel power amp. If you are committed to stereo plus sub, look at the Harman-Kardon HK-990 http://www.stereophile.com/content/harman-kardon-hk-990-integrated-amplifier
I am surprised that you have dismissed AVRs as there are several that should easily drive your LSi9s. Be aware that, since all the amps in an AVR are running on the same power supply, maximum output per channel must vary with the number of channels being driven. OTOH, since the multichannel signal sources never drive all the channels equally loudly at any time (except during testing), the 2 channel or 3 channel ratings are probably more representative of how the AVR will perform in your system.
Also, bi-amping will not be of any signficant value in increasing power output. If your currrent amp or AVR is inadequate, just get a much bigger one.