To Bi or not to Bi? That is the question

I foresee two problems for you:

1)The volume you get from each amp may be different, so you end up with too much or too little bass.

2) An amp designer I know calls this "fools bi-amp" and believes that driving an amp full frequency range and using only part of that frequency range causes audible problems, esp. for the tweeter amp as there is a lot of energy in the bass frequency - which the tweeter amp isn't getting rid of but IS trying to produce.

Get yourself an active crossover, even a cheap one for now - you can always upgrade it later - I REALLY recommend this as a major gain.
Worst case, a good car one can sound OK for now - I have seen one powered by a spare car battery that was re-charged every couple of weeks!
Do some homework about cross-over slopes, use the same slope (1st, 2nd, 3rd or 4th order, also sometines refered to in dB per octave) and crossover point as the crossover in your speakers.
You can also get different alignments, I would reccomend Linkwitz-Reilley.
Don't worry about mixing amps, as long as you think the sound character is simmilar at the point where they will cross over.
I use VTL 100 monoblocks (tube), crossed over at 400 Hz to New Zealand made mostfet 250 watt per channel then to a 215 wpc mosfet parasound in bridge mode at 80 Hz to drive the sub.
This is using an active crossover. Nobody has ever commented on the mixture of amps and some people into live and studio sound professionally have been unaware they were listening to a multi-amp set up - when told, they were not suprised as they thought it "sounded too good for a passive cross over".

Only in "hi-fi" do people seem to insist on using one amp full range.
Not only does it make an amps life hard, passive crossovers are a nightmare. Expensive (VERY) to do well, hard to drive and they consume a lot of power that never even gets to the speaker drivers!!!

Hi Marakanetz,

My 100 monos are very early and offer ultralinear only, a sort of compromise between pentode (being EL34 type tubes)and triode.
Your ears will very soon tell you which is right, but if you are crossing over to a solid state amp (mosfets being slightly tube-like in sound make life easier than bi-polar transistors), then I would expect tetrode to be better.
Tetrode is closer to solid state in being less "lush" and edging both amps towards each other in sound helps. VTL's are good as they do not have a particularly "tubey" sound.

Anyway, trust your ears - you have to listen to the result and I have NEVER heard anything that sounded totally right - especially immediately after listening to live music!

One thing I have found usefull is (assuming you are male) finding a woman (preferably fairly young so the top end of her hearing hasn't gone - for that reason avoid party animals as well) prepared to sit down and listen to female vocals.
They have much more sensitive ears than men in the vocal range and everyone has a good live reference for the human voice.
I have found the acid test is their willingness to listen for long periods, assuming they have the time. This at least tells you that there are no significant nasties or annoying discontinuities in the sound that males can't quite hear - but are fatigued by.

I understand your love of good bass. If it is quick and clean it does provide a great foundation that adds to the pleasure of the music.

Best of luck and trust your ears.