Hey guys-just a suggestion......If you havent cleaned the jumper wires between the high and low inputs-DO SO! I went to bi-wire mine the other day and realized there was green stuff on those wires and the difference was dramatic in the sound. when I cleaned them out. The soundstage opened up, bass got tighter, and I could hear differences between cables, CD players and just a higher level of resolution in all my recordings. I found myself listening for hours. In fact, these speakers are 25 years old so I'd go through all the driver terminals and clean them all. Craig Labs make a cleaner called Deoxit and a contact enhancer called Progold you can get at Radio Shack or partsexpress.com that I use on all my contacts.
Also I've damped the rear sound radiation from my 2.5's. I disconnected my rear tweeters and put acoustic foam over the midrange emim's so output comes out the front only. You'll need to put a 3-5 ohm 10-15 watt resistor in the tweeter terminals or the output of the front emit will increase. This is a personal preference but I find in my small living room they image better this way.
Another thing about amps, I ran my 2.5's for years on a NAD 3020-20 watts per channel! They wouldn't play that loud but the NAD was happy with a 2 ohm load. So whatever you hook them up to make sure the amp has CURRENT capability. Granted power does make these come to life and Infinity recommends 100-300 watts per channel. Tubes sound good but you're into big bucks for a tube amp that's happy with 2 ohms. Get a tube preamp or the Musical fidelity tube buffer. I've never had the bi-amp crossover box so I can't comment on that. Happy listening.
Ted