Very bright SC and IC with coherence in imaging, soundstaging and timing

You need tone controls or other frequency equalization.  If you can't deal with that, then just accept your loudspeakers for what they are.

+1

You might try different tubes in your amp.New reissue tubes will have a brighter sound than most nos.

+1 re trying different tubes in the amp. Also, what amp is it, and have you tried all of its output taps?

I suspect that the impedance of the speaker, which I presume is made by Cambridge Audio, rises significantly in the upper treble region compared to what it is at mid and low frequencies. If so, an output tap designated for higher load impedances is likely to result in a brighter presentation than a tap designated for lower impedances, to a degree that is dependent on the output impedance of the particular amp as well as on the degree of the speaker’s high frequency impedance rise.

If you already haven’t taken steps to optimize the amp/speaker impedance match, IMO doing so is likely to make far more of a difference than changing cables. As is some experimentation with different tubes.

Regards,
-- Al

Lots of requirements, lots of limitations, fighting physics, not much $. Bad combo. If you specify your amp, source, and tubes and wires you’re currently using it would help significantly in generating more useful recommendations here. Taking a shot in the dark on wires, maybe look at DH Labs Q10 cable and Silver Pulse interconnect — silver-plated copper might be your best compromise at this price level. Best of luck.

try mid level nordosts or mapleshade clearviews

I will try eq.

still open to cable recommendations. It’s a hobby ...

I have a couple pairs of Amadi Maddie Signature silver wire ICs and a couple pairs of Darwin Silver or Ascension silver wire ICs that are both very detailed, open, will light up the sound a little but with no harshness.  They are significantly better sounding than good cables such as Morrow MA-3 or 4, Crimson, mid priced Audioquest--have had all of them and some others.  Magnan, DNM, etc.   Am currently using Teo GC II doubles with the Schroeder Method and JW Reference doubles with the SM in my best system.  They make a great combination with my system.  

Bob

Just out of curiosity, does it have a dip in the frequency response at about 2Khz?

I am surprised the designer used that driver and didn't accommodate for it in the crossover. I would be interested in what the bass driver is that is being used with it?

If you ever get to hear a speaker with the SEAS Exotic T35 X3-06 I think you might like it. It won't go quite as low as the BMR, but it's exceptional for a tweeter that is regarded as possibly one of the very best. 1500hz to 25000hz

If you want to try the cable route, I have cables that I used to do exactly this. I just retired a system where I used Bolder M-80 cables, so it can be done. I will be selling them, but they fail your boutique criterion and the company folded shop. Copper & silver amalgam; 4 solid naked wires with slight twist. 

Kimber 8 tc Litz is very good for each wire is isolated from the next 
the 12 tc  is a bit better still and great value.

Any speaker wire or interconnect that adds 3dB at any frequency is defective.  Might I suggest the Schiit Loki? 

audioman581,666 posts07-13-2020 4:38am"Kimber 8 tc Litz is very good for each wire is isolated from the next
the 12 tc  is a bit better still and great value."

Actually, the Kimber 8TC is not true Litz construction. It's made up of 16 conductors that are indeed isolated from each other, but each conductor is made up of numerous strands (Varistrand) that are NOT isolated from each other.

The benefit of the Kimber is not from Litz (or not Litz), it is from low inductance.

I second the Schiit Loki, using EQ will be more accurate than trying different cables. And the Loki is transparent when wired into the system.

If you must keep the speakers then sell the tube amp and go S.S.
Always brighter on top. 

I would not discount the suggestion made by @almarg .
Have you optimised the impedance between amp and speaker by trying both 4ohm and 8ohm taps? 

Can you tell us what amp you're using and tube type? A tube change is more likely to increase high frequency energy rather than changing cables; ie, NOS Sylvania tubes are known for their extended highs with great detail.

20 years ago I would have recommended Nordost cables, but I have not listened to any for the past 15+ years and assume that they have evolved over time.

Exposing the make/model of your tube amplifier would probably make for the best advise (aside from EQ) as small signal tubes used in gain stages can differ greatly as far as tonal balance goes.

DeKay 

I own a complete set of Nordost Heimdall II cables and like them very much, but at the suggestion of a friend I purchased a DH Labs Mirage USB for a second system. It's so good,  it has replaced the Heimdall USB in my main system.  I've done an extensive a/b test and they're very close, but the Mirage is a bit more lively.  I've since purchased a DH Labs D-110 AES/EBU cable with similar results.  So, now I'm curious about their XLR (Matrix Air) and Speakers cables(Q10)?