Interconnect suggestions for Audio Research Ref 5SE?

I have moved the speakers in about 6” each and have reduced toe in. This has resulted in a more focused though somewhat crowded soundstage and doesn’t really address my concern.

I’ve concluded, for now anyway, that the cables weren’t the issue either…all the various cables did was introduce their own character and new variables…perhaps mitigating the top end but introducing other traits I haven’t been entirely satisfied with either.

Another member suggested I go back through everything. As the pre-amp is new to me, and as I did not have this issue before, I’m taking a closer look at the pre- noting the previous owner mentioned some top end brightness compared to another pre- he had on hand. I also see that neither of the tube sets that came with the pre- are from audio research. Not that tubes can’t be sourced from elsewhere, but it adds a variable right now.

Several have remarked that cables should be making only small differences. So, right now I’m going back to what I knew and liked before,.. Wywire. 
 

I’ve pulled the pre, tried to clean things up a bit more and am substituting in the other tubes to see if that does anything. Will almost certainly order a new set of tubes so can at least do away with that variable. And go from there..

I have also bought a used pair of Wywire Diamond XLR to go with the other Wywire cables I have. They should arrive soon.

At this point am a bit spent out and need to sell some stuff before I can go buying any more!

The weird thing to me is that you’re finding an audio research piece to be bright. If anything the highs are somewhat muted and dark. Not a ton but more than I prefer. The caps they use are not my favorite.  
I had an ls28se. I went through everything while I had that pre. AQ thunderbird, Nordost Tyr 2, shunyata sigma x, Zenwave, some cardas, Clarus, audio art, fidelium and Furutech 

sigma x has a copper timbre but is smooth and somewhat rounded and for some reasons tonally displays itself more like silver. Wasn’t a fan it was too different. 
thunderbird was very good with very very minimal distortion and locked in imaging but it made everything sound hard

tyr2 I wasn’t impressed with was almost too normal with not enough detail. Really liked their pc in the dac a while back though

cardas is golden and fuzzy and and just too golden. However, there are some absolutely beautiful timbres  that make you wonder how some of these other super high end companies not getting this right like this. Ultimately fleshed out nature of its purity of copper just gets boring real fast as it’s a vivid coloration. 
 

Zenwave d4.2 actually reminds me of the audio research sound a lot.  solid state sound with tube like qualities. Organic, slightly bloomy and somewhat dark.   It’s imaging is very good but the soundscape it sits is panoramic    Detail is very good  he has an even higher end model that sounds similar but not as dark, added textures  I’ve used old cables that seemed like they had extra texture that is almost like they started to patina inside.   But this sounds good and not a negative

Clarus crimson. Strong organic, dark and bloomy, hefty copper timbres.  Detail is best I’ve heard for a copper cable.  But I would not add this to an already dark system. 
synergistic research wows you initially but it’s artificial and man does the silver come through in timbre hardcore

Furutech project v1   It’s not a cable   Cables are bad     Does need  a few hours of runtime before it starts its disappearing act

Also wireworld platinum eclipse 10

this ones weird. Definitely focused more on low bass than high bass. This is a capable cable close to the top like Zenwave and shunyata but different. I definitely preferred it more than the shunyata. It can be fast but then it has these weird soft slightly fuzzy attack and texture.   Detail was good but just slightly behind d4.2