Audio Research LS17 vs First Sound Presence MKII

I am looking to purchase a tube preamp. It would be my first experience with tubes. My system is Coincident Total Eclipse speakers, Pass Labs X250.5 solid state amplifier, Classe Model 6 solid state preamp and Theta Miles cd player. The Music that I like is blues and classic rock. I am looking at Audio Research LS17 and a First Sound Presence Mark II. I have been using balanced interconnects between the cd player and preamp and also between the preamp and the amplifier. The LS17 has balanced, First sound does not. I like dynamics, imaging, and spacious sound stage that I have on my system now. Looking to have a more lifelike sound with removing a little of the solid state edginess. Any thoughts,comments, recommondations or experience of owning these peices would be appreciated.
I have never heard of First Sound Presence but I have an LS17 and love it; it is being replaced by an LS27 though. Eventhough my monoblocks are balanced and single-ended I prefer running single-ended between the preamp and amps; the LS17 has a lot of gain and it just sounds better to me running single-ended.
A year ago I was looking into tube preamps too, and the First Sound was very high on my list...second, actually. I ended up with a Lamm LL2 deluxe, and I'm VERY happy with it. The ergonomics (or lack thereoff!) are similar to the First Sound, and is also RCA only. I don't remember why the LS17 wasn't in my list.

RCA is not inherently inferior for all systems and all conditions. Sure if you have a very long IC and live in RFI/EMI hell, but do you? Mr Go, maker of the First Sound doesn't think there is a technical advantage per se; just depends on the implementation. So, do your amp and CD player sound equally as good through RCAs or XLRs?

In case you haven't seen them, Soundstage had a good series of reviews of approx $5k tube preamps around year 2000. They were helpful to me as they compare units.

Are you buying new? If so, then try to audition.
I was buying used, so I took my time to search the virtual systems and forums to find people with these preamps and a similar amp/setup to mine, and got in touch. I even found a person who had the same amp and speakers I have! It takes a lot of time, but has been worth it for me.

My two cents
I am purchasing a First Sound Presence MKII preamp. Everything I see on reviews and opinions is great. Thanks to those you posted here.