Conrad-Johnson PV 11 preamp tube dilemma

It would also help to tell us what TT, cable, and cartridge you are using.

So many combinations of tubes shouldn’t sound dull.
I’m really wondering if the Morrows need more break-in.

In addition, I read the PV11 manual and your preamp is phase inverting. From your listening position, does the image sound focused or is the soundstage smeared and coming from different directions?
If phase correct, there should be good detail, and the image should should not be dull. 

One of the MA4 cables is two to three months old.  The other one is new and had ten days factory break-in, but certainly needs a lot more time.  This is the one that caused the problem. I understand it will probably get brighter as it breaks in.  The thing is, the current configuration sounds so good, at least, with CDs, that  I don’t want it to change!
Turntable is an extensively modified Rega RP3.  Cartridge is a typically mellow, but excellent Grado Sonata.  Speakers are modified Dalquist DQ 20’s. Amps are NuForce Ref 9 v3 monoblocks.
I know the amp is phase inverting.  I’ve dealt with it.

Nice cart, I like the Grado sound. OK, so you do need to open-up the phonostage with some dynamics and detail. In addition to my advice above, I’ll add that you don’t need a Mullard in your analogue chain.

Some other 12AX7’s; Siemens (good extension, but Tele’s are better), Sylvania (dynamic, transparent and airy on top), Amperex/Philips (same factory, many different choices). There are Sylvania 12AX7 and also 5751’s. The 12AX7WA Sylvania military is a popular tube. Some Sylvania’s can sound bright, so they should be mated with a less extended tube.

I guess I have to ask the obvious but if changing to the morrow ic caused such a dissapointed sound result that you felt you needed to start tube rolling might it not have been better to just have put the original ic back in the system?

Or were you changing ic because you disliked the sq anyway?

uberwaltz,

What prompted me to use a Morrow cable in the first case was that another piece of equipment I had, benefitted from a Morrow product.  
Then, since that cable (between the preamp and the DAC) worked so well, I installed another identical cable between the preamp and amplifier.  That’s when the dullness occurred.  I happened to have a couple of Amperex 12AU7’s tubes lying around.  I knew them to be brighter than the  Telefunken, so I thought I’d give them a try.
Voila!, the sound opened up.