I'm going to get in trouble for saying this....but this is how I would do it.
Hook up the DVD-Audio player through the digital connection. I know, DVD-A doesn't have a digital connection. The discs, however, will play on a regular DVD player and output a regular digital output. It may not be as hi-res as it can be, but you will still get the information from it.
Hook up your new SACD player through the ICBM into your receiver/pre-amp. This is the only way you're going to get the advantages of a SACD. If it's a good disc, it will sound great.
Now, let me offset my idea by saying this also. Any hi-res disc is only as good as the recording that's on it. Duh... Here's my reason: It's only going to truly blow away your regular cds if it was recorded at a high enough resolution throughout the entire recording process. You'll notice that most SACD releases come from either DSD recordings or from the analog masters. That's because these recordings haven't met a PCM bitstream yet. I believe this point is really overlooked by most people. Let me put it another way. Let's take a regular cd and put it on a record. Now all the analog people say, "Yippee, it's analog!" Umm, not quite. The recording has still experienced "ugly digital." This is the equivalent of taking a regular cd and putting it onto a SACD. I know, plenty of people out there swear by "upsampling." Personally, I don't get it. There is a value to have DACs that can handle higher bit rates processing your audio but "upsampling" still doesn't make sense to me.
Wow, sorrying for rambling like that.
Ok, back to your dilemma. I would say to use the money you saved on your players and put it towards a second ICBM. Then put together two systems...one for home theater and one for music. Dedicate the DVD-A player towards the home theater system and the SACD player towards the music system.
Unless your receiver/preamp has two seperate preamp ins, the only options I can think of are my first suggestion or cable jockeying.
Good luck!