Hi I use to have my NHT 2.5i bi amplified with an NHT SA-2 subwoofer amp running the R and L lows and a KST-100 running the R & L highs and it worked out pretty good since the SA-2 has a crossover and volume adjustment therefore I can fine tune the base response. If you want to know more on biamping here's a very useful link, check it out-->http://www.sound.au.com/bi-amp.htm
Happy listening