phonostage driving 2 pre-amps - any ideas?

A friend has two systems.
The cd player and tuner from the main system are linked to the other but he wants to be able to play vinyl through both systems.
I doubt very much if his Quicksilver phonostage will drive 2 pre-amps at once.I recommended if he can live with playing through either system (one or the other)a high quality switching box (a misnomer I know)would do the job.
The cartridge on his his Linn is a high output mc - Sumiko Blue Point.
I have a Quicksilver step up and wondered if I fed his stage into this, hiking the signal by 20dB,I could then split this the signal from this to drive both systems?
Possibly disasterous if the full output goes to one system?
For me I'd live with cd/radio - who wants to be at the other end of the house when an albums in the run out groove?
Crazy but he will not be swayed.
Any thoughts/suggestions appreciated.
Rgds Simon
wouldn't connecting the two preamps together by taking tape output from one to a line in on the other be just as good as any switch box you can find, or your Quicksilver suggestion?
Bdgregory - pure genius!
Not sure if the Linn Unidisk which is in effect his main
pre will have a tape loop but I wish I had thought of that one.His stuff is all too high tech for me to cope with - the Sondek (which I had just set up) had me cringing till I realised the Unidisk was set for 5.1 surround.
Thanks,will post the outcome.
Rgds Simon