AR LS7 v SP14

My experience with the SP14 has shown it to be a very detailed, clinical and bright sounding pre-amp. I've no experience with the P270. The LS7 is a nice budget tube amp, not overly warm or bright. Tube changes can make a difference in its tone. However.....

I wonder if you are travelling down the right road. You want to replicate the sound you heard in the demo room, however unless your room, system, and set up are identical you never will. You need to tackle your room on its own merits. The most critical issue is speaker set. Have you explored proper set up issues thoroughly yet? If not, do so before you spend another dime!

I respectfully disagree with the Newbee's summary on the
SP-14. I owned one and found it to be neutral, spacious,
and airy with excellent bass. I previously owned an
Audio Research SP-6B which was highly regarded in it's
day. I found the SP-14 noteably better in several respects.
The SP-6B had a much higher noise floor, loose tubby bass
and a limited high end extension. I've owned an number of
preamps over 30+ years and I consider the SP-14 one of the
better units. It also has a wonderful phono stage. I can't
comment on the LS-7 as I've never heard one.

I can't speak to the SP14 but I owned the LS-7 for less than a year. It is one of AR's weakest efforts although none of their linestages (and power amps for that matter) are particularly noteworthy. Given other choices such as Joule, VAC, and even Sonic Frontiers, AR stuff wouldn't be my choice again.

I use the SP14 as the phono stage in my system. It is quite lively, detailed and dynamic with good bass drive. Its line stage in my experience is pretty neutral in relation to others I've had in my system. The Classe' DR-5 is dark, the Melos SHA-1 is slightly less so, the Forte'model 2(which I auditioned extensively versus the PSE HL-1 which I found to be almost indistinguishable with female jazz vocals) pretty neutral as well. I find the sound of the SP14 to be pretty modern in that regard (not tubelike or obviously solid state, just gives you the music in a natural fashion). Very similar to the current ARC LS16 MkII(my current linestage) in overall coloration although I might add that the SP14 is a bit stronger in bass drive that the LS16 II. Its weakness in my system was a slight foreshortening of depth(which is one of the areas that the LS16 II is superior). I don't have experience with the LS7, but can confirm that the SP14 is an excellent overall performer and a bargain at used prices.