My first set of separates was a NAD 2600A, 1300 and I believe a 5100 CD player on Magnepans SMG As back in the late 80's. At the time I was very happy with that system being out of school. Nothing wrong with a 2600A amp if that's where you budget is. Only caution is the caps but I bet they're fine and if you have to replace them it's an easy task and they're not that expensive and readily available. I doubt the 2700A was that much if any better and they weren't made as long so probably harder to find one anyway. I don't follow those amps anymore but guessing $250 +/-? If you don't like it you'll be able to resale and likely not lose much if anything.
I remeber on on the back it has a soft clipping switch which sounded best with that turned off. The potentiometers on the front are very poor quality and I bypassed them and that helped the amp as well; easy to do. At the time I felt the 2600A was more musical over a stock Adcom 545. The Adcoms where a lot easier to mod and doing so they could be a better amp.
I will add if you want a nice amp which later I also once owned, look for a later B&K ST-140 which was a 100 watt amp. The B&K can be had for probably the same money or less and will walk over the NAD. The NAD has about 10X the parts of a B&K. For a vintage, little killer amp the B&K is hard to beat for the money. I really enjoyed that amp and I used it on Apogee Centaurs which it drove them nicely.
Good luck
