Can I use a multichannel amp to bi-amp my speakers

I use single Kimber 4TC unterminated wire so part is spliced for lower terminals and part is for upper respectively on the speaker end.
It looks like biwiring, only I don't have to use jumpers.

A multichannel amp will only work to bi-amp if each 'amp section' has it's own input, which (as noted) requires an active xover.  In my case, I've dispensed with a pre-amp, gone to active eq, and use a matrix (actually a pair) to control inputs and how various elements interconnect.

I really don't miss a stand-alone pre-amp, BTW...

put your money into a better 2 channel amp rather than a mediocre 4 channel.

I had a nice Theta Intrepid which I used to biamp Meadowlark Audio Heron (hot rod version) and BG Corp 520DX.  I ran directly from the source, a modded Oppo BDP 83SE, using the 2 channel outs and the FR/FL to drive 4 channels of the amp.  I thought it sounded very good.  The Theta had a beautiful top end, lots of air and detail, very delicate, mids were clear and slightly warm, while the bass was decent.  It never drew attention to itself but you never felt deprived either and the BG's are intentionally rolled off early.   You could also go with a preamp with 2 pairs of outputs to run the 4 channels.  I also had a pair of Pathos Classic One MK III integrateds.  I had 2 so I could bridge them but I ran them as 2 stereo integrateds briefly for the hell of it.  It was better than a single stereo amp but bridged was way better than 2 in stereo for biamping.   The active crossover might improve things.  I have no experience with them so can't comment on how they'd improve the sound but an active crossover isn't necessary with most speakers.  I'm not familiar with the Gershmans but I've biamped the Meadowlarks, BG Corps, and a pair of DIY 6 driver Legacy Focus clones and all did well biamped.  Just make sure you get a good multi channel amp and don't skimp on the cables.  Good luck!

Single amp probably best way to go and both Sim and Modwright very good choices. Nordost now supports a single run with jumpers to the other set of posts rather than a bi wire set. When upgrading my Nordost Valkerie (sp?) to Valhalla series 1 I went this route on recommendation from dealer and nordost and have been very pleased with result