How to

I plan to use my mint, Pioneer SX-1010 receiver (amp section only) to drive front L/R speakers. I want to buy a 3 or 5 channel amp to drive surrounds and possibly presence speakers.
My Yamaha RX-V1400 sounds pretty anemic compared to the Pioneer so I rather not use the amp -- just the pre-pro sending Fronts to Pioneer and the rest to new amp/amps.
I have a budget around $1,500.
Assuming I can't listen to a variety of amps locally, what's the most reliable way to select a multi-channel amp so that the surrounds will "blend" well with the richness and depth of the SX-1010 on the fronts? I'm not sure what specs are most important if specs are all I have to shop by.
Pioneer SX-1010 amp specs:
100wpc 20-20k
Power Bandwidth - 5Hz-40kHz THD <.1%
Freq Resp - 7Hz to 100kHz
Input sens/impedance - 1V/50k ohms
Damping Factor - >50
18,000 micro-farad capacitance

Any tips are welcome.
Finding a amplifier to match the sound of your vintage reciever may be a difficult task. When building multi channel systems, best results are achieved by using the same speakers and amplification for all channels. At least stay within the same family/brand if possible. Perhaps
Pioneer once made 2 channel amps using the same topology as the SX-1010? Others may chime in with a dinfinitive answer. That said, I would suggest going with something completely different. There is a nice B&K 5ch amp up now for $575. That amp offers tons of value, good sound and tough USA built.