Dev, I will try to be succinct. The Spectron is a very revealing amp; my first one replaced tube Sonic Frontier Power 3's and the increased clarity was obvious from day 1. Over about 500 hours the amp settled in to become clear, open, coherent and presentation was the most lucid I have heard in my system. As time went on I found that as the Spectron opened up, there were was a degree of stridency I was previously unaware of in combination with the REF 3.
During this time I did change my speakers as well to another self-built design based on the GR Research OBI 7's, which are dipoles and also extremely transparent and lively. When I exchanged the REF 3 for my Line 3 (I owned both at the same time) I was able to compare directly and the difference was immediately obvious and I could not go back to the REF 3 without feeling it was edgy, brittle etc in comparison to the Line 3 which has always been a great controlled neutral pre and suddenly the Line 3 becomes really alive and the REF 3 is over the top for me in my system.
I truly believe the REF 3 IS A WORLD CLASS PREAMP, but as the Spectron found its groove, the REF 3 seemed out of place. I now believe my Line 3 has a much better match as the music just flows - not a highly quantitative assessment I agree, but emotionally I have a clear preference. Since the REF 3 goes for 2 X the $ of the Line 3, I sold it. Based on my experience I would tend to recommend a preamp for the Spectron that is "smooth and neutral"" (whatever that means) versus one that is forward and bold. The ARC house sound has not shifted that much over the years and there are many comments here on that - BTW, I am still a big fan. I know Simon likes the BAT gear to with the Spectron and now I see (hear) why. If I was looking at SS, based on my limited experience I would choose a Sim Audio P7 or P8 rather than a Classe for example. I hope you get the drift.
So much depends on other system components it really is hard to compare. I tend to use silver IC cables for example because I favor an open transparent, energetic sound, rather than a bloomy, softer sound. Most of all I value coherence and tonality and I don't like a smeared or distorted sound such as SE Triodes - that should trigger a couple of flames!
As to changing PC's and speaker cabling etc; that is inevitable when you go from stereo to a monoblock configuration as I have just done. I should add that in the stereo mode I used the remote sense cables, no idea if that had any impact on the REF 3 presentation.
Steve