Used Audio Research Preamp Options

 I have to agree with statman. I have also owned a lot of Audio Research preamps over the last 25 years or so. If I only had $2500 to spend on a preamp, it would be an LS25 mk2. I owned one for years until I bought my Ref 5se. It is a killer preamp for the money. The mk2 version uses the 6h30 tube instead of the earlier 6922 tube.

 

 I have also never heard an LS5 in my system. But I believe it is all balanced. ARC sold a converter to use with it called a BL1. It convert single ended into balanced..

The LS models are line stages where the SP models have built in phono stages. The LS3 is solid state. The higher the number the newer the model.

 The back of the  LS25 is the same as the Refs wit a full compliment of both balanced and single ended inputs and outputs.

Preamps have come a long way n the last 20 years. I have owned both an SP8 as well as  an SP9, The LS25 mk2 is much better sounding than any of my previous ARC preamps. When I first got my LS25 mk2 I was amazed at just how much better it was than the original LS25.

Some years ago I was offered a really great deal on an LS27. I took it home for a week to hear in my system. I passed on it because I felt  it was a sideways move. The LS25 mk2 is really a sweet preamp. It is far more detailed with a larger sound stage than any of the earlier models save the Refs. Don't get me wrong , my Ref 5se trounces it. But then the Ref 5se trounces just about everything.
  
If you can stretch a bit you might also want to consider a Ref 2 mk2. Big brother to the LS25 mk2. If you can find one, this is also a really sweet preamp. I could have easily live with this one for life had I not heard the Ref 5se.

  

 You can search multiple sites using hifishark.com

 There is an LS25 mk2 for sale on the AudioCircle Marketplace for $2500.

 There is a Ref 2 mk2 here on Audiogon for  $3,250.00

 Both prices are probably somewhat negotiable. 

 You are comparing an NAD C165BEE to no preamp. Go borrow an Audio research preamp from the dealer for the weekend. Then do the same test. That will give you a much better idea of what a top flight preamp will do for your system. I doubt it will be as close.