Mullard E188CC - but with tight bass?

I just digged into tube rolling a bit as my dac (Lab 12 Dac 1 Reference), which is using ECC88s and variants in its output stage, needs a shot of energy and atmosphere.

The stock tubes were 6922 Electro Harmonix. Well, they were okay but nothing special and lacked a precise bass. I changed over to the legendary Amperex bugle boys. My dear, that was an excellent, precise and powerful bass, but the mids were too upfront and I couldn’t relax with them.

Next one was a pair of Siemens E188CC from 1966. Excellent tube, great dynamics, but a bit too cold and lean for my taste and the bass wasn’t as good as from the bugle boys. Finally I now got some RTC E188CC from the early 70ies. Wow, that was the midrange I was missing all the time. Absolutely rich, voluptuous and full of textures. Really amazing, just like the 3D soundstage. The only thing that bothers me is the bass. Again it’s not 100 percent tight and precise enough. Maybe on par with the Siemens but not with Amperex (I have to admit I just used them for 3 days now. Maybe the burn in process will improve the bass but who knows).

So my question is - is there ANY tube out there with such an impressive rich, involving and delicate midrange like the RTC E188CC combined with a tight and precise bass like Amperex? What about the Mullard E188CC - or is it the exact same tube? Valvo, Genalex? Open to anything but I’m not looking out for a compromise regarding the midrange.
@lowrider57 I thought and hoped so even though the bugle boys didn't show any improvements through a process of around 100 hours of burn in.

In contrast to this the Mullards bass sounded much better yesterday evening. So when do you think can I expect them to be fully "broken in"? 
Telefunken, Mullard and Tungsram. in that order. If you haven't tried Telefunken, you should. Don't cheap out, make sure on the vendor. Tungsram is a true diamond in the rough too.

Mullard is like GE to me they make great valves and they have their name on a lot of so so valves also. Make sure, the older the better for the most part.. 50-70s some of the best ever made. I like the BP and BB Mullard produced.

Marconi is another hit and miss but a great valve too. They just have to be tested.  In a preamp though, they can last a lifetime..

They ALL produce what is there, like a good preamp valve should. I've never used preamp valves to do anything other than get the WHOLE signal to the power amp section, without bass bloat, forward mids or HF boil.

Tellies,  Great RCAs or Mullard in a perfect world.. I've used the same valves for 40+ years.. I know what they do..

Tight BASS.. decouple your speakers all of them.. That would be the first thing I would do. Then 1/2" at a time position your speakers. Closer to the wall for more bass, away from the wall for less. 

I think valve swaps would be the last thing to do..  No tone control either? I do things a little different, I think.. :-)

Barista, I think my Mullard RTC 7308's needed 60 hours of burnin. You should have very good bass extension by then unless something in your system is limiting the low-end.

And the heavy engineer makes a good suggestion to 
tighten up the bass.

I have the Mullard RTC 7308's as well plus the Amperex 7308's...both from the 60's.  They all sound great but the Mullards do have better bass and deeper extension.  Just keep in mind that compared to 6922's the 7308's have slightly lower gain. It has a peak gm of 11,500 micromhos where the 6922's peak at 15,700 micromhos.