ARC LS-5 vs SP-10/11 for Plinius SA-102

Having heard all three in familiar circumstances, I think the LS-5 would be my choice, given that you don't need a phono section. The LS-5 seems to my ears to balance the glorious classic tube sound of the SP-10 with the accuracy of the cooler, more neutral SP-11 to give a better overall presentation (kind of a best of both worlds thing). I've always felt the LS-5, particularly the revised versions of it, is one of ARC's best products, and a little underrated. Plus if your Plinius has balanced inputs, the LS-5 has balanced outputs, as I recall (you can get a balanced output from the other two using the inverted and main outs with some adaptation of your interconnects, I think, but it's a hassle).

tgm: Don't fall in the "newer is better" trap that the manufacturers and mags would like you to believe. My Jadis preamp is from 1995, my Jadis amps from 1990 and I'd stack them up against anything out there. While there have been improvements in parts over the years, ARC is good about updating their units and bringing them up to spec when you send them in for a checkup, and Brauser's point about upgrading through Great Northern(?) Sound Company--I'm thinking of Steve Huntley--is a good cost-effective way to bring a fine commercial design such as the LS-5 (not the 15, I've not listened to that one at length, I presume that was a typo) up to state-of-the-art status if you really want to. I'm not sure how it will sound mated to the Plinius amp, as I've not heard that combination, but in my prior listening with this pre and other ARC preamps they fed solid-state amps with no problems whatsoever. As Blauser says, the LS-5 is a very musical preamp, I think that would be ideal with your speakers, which are designed more for the music lover rather than the "boom and sizzle" crowd.