Need more inputs in preamp, what to use?

I'd play some discs through your Benchmark before deciding that you need to keep the the Sony hooked up just for its playback of SACD. It is possible that Redbook playback through your Benchmark will be good enough or superior to the Sony decoding SACD on its own, despite the data density difference. If there are titles on single layer SACD that you need to hear, then this option would, of course, be moot.

I would look at DBX 200 and 400 route selector. They are usually easily found on ebay. Good luck.

http://www.audiogon.com/cgi-bin/cls.pl?accstwek&1288835877&/Manley-Skipjack-high-end-4-to-

How about Goldpoint?
http://www.goldpt.com/sw4.html