The XP-10 was the single box preamp replacement for the predecessor Aleph P preamp. If you can stretch your budget say +$1000 bucks, get a preowned Pass X0.2, which is the 3 box preamp from Pass. This 3 box arrangement in that range of XP-10, XP-20, then X0.2 is the superior rig. I bought one new years ago and paired it with my room heater Aleph 1.2 (200 wpc Class A) amps. After break in, it was a glorious paring. The synergy between Pass components is stunning. At least to my ear, the thing that really capped it was a pair of JPS Superconductor XLR interconnects; THAT brought a very black background where images seemed to just pop out of thin air. For me, it was stunning. I know money can be tight, a Pass preamp is a mighty fine buy. Now, as for the sound, you must like that bit of romantic midrange that tubes will bring. The XP-10 is not the end all of deep bass. Don’t expect low end presentation like an old Krell (forward presentation, dynamic and low bass intensity). If your taste is in the realm of a laid back presentation (behind the speaker presentation) in sound stage, and you like music that lies in more in acoustic instruments, jazz, especially string instruments like a guitar, harp, and the such, this will bring a nice bloomy sound. If you like a more neutral sound, meaning something that is "cooler" or "white washed" in the mid-range, this XP-10 might not be the rig for you.
If you like more a neutral sound, perhaps something like Sonic Frontiers Line 1 or Line 2 (uses 6922 bottles), maybe an Adcom GFP-750 (Stereophile Class A back in the day), or even a vintage Audio Research tubed preamp, which will tame or chill the midrange just a hair. If you do get that XP-10, I’d highly recommend buying say a Pass amp in the Aleph 3 (30 wpc Class A - a mini room heater), or the Aleph 5 (60 wpc Class A, slightly better room heater). Once you step into the Aleph 2, which are monoblock 100 wpc units, then the cost escalates quickly and you are no longer in lower cost preowned gear.
If you want something a bit less bloomy in amps, a Mark Levinson ML9 kicks ass. A better Levinson is the ML27.5, which is astoundingly good. Those MLs make anything sound good, especially if you have tough to power speakers like flat panel models like Apogee and the like. If you want to stick with a Levinson all in one, a Levinson 383 is good stuff also. Just make sure its capacitors and filter capacitors are replaced. Those Levinson amps, they get super hot, as in hot enough to cook an egg on. That’s what you get when the bias on the output devices are turned up for Class A operation, but ahhhh, that smoooth midrange is to die for... Happy hunting, and sorry for the rambling... :)