Speaker Cable Recommendation

For a great value and great sound try Kimber Cables, had them for a few years. Cardas is absolutely outstanding but fairly expensive, my whole loom is now Cardas Clear and very happy with results. 

Also I treated my room with Acoustimac panels and made a world of difference and not expensive at all, one of the cheapest ways for a big difference. 

Parts Connexion will make you a custom pair of Duelund's for less than $400.   I recommend 12 gauge, sans connectors (bare wire).  I've been using Duelund in both of my systems for probably 5 years, having replaced and outperformed considerably more expensive Auditorium 23's.  They do take about 150 to 200 hours to break in, so be patient.  

https://partsconnexion.com/products/dual-dca12ga-2x12-awg-tin-plated-stranded-copper-oiled-cotton-speaker-interconnect-cable-black?_pos=6&_sid=cbd50cd57&_ss=r

+1 @noromance 

Have you rolled those 12AU7 s?

@marktheshark 

Try some Tungsram NOS 7DJ8 tubes in your BHK pre amp.  I use them in my BHK Pre amp and BHK 250 power amp.  In my system, the stock tubes sound thin; the Tungsram NOS 7DJ8 tubes sound "fuller" and more natural.  I've tried other brand 7DJ8s - none of them sounded as good as Tungsram.

Good Ole Kimber Kable 8 or 12 TC is surprisingly great at fixing this kind of issue. I'm not a fan of cables with boxes on them either. Cables are tone controls, its important to find ones that make the changes you like.