Transcendent Sound Grounded Grid Preamp upgrade

I've a Transcendent Sound Grounded Grid Preamp which sounds decent, but no match for a friend's Manley Jumbo Shrimp loaned me. I understand the price difference. Has anyone tube rolled this preamp with significant improvements?
I'm running an Audio Quest AC2 power cord.

It sounds congested and not as dynamic as I had hoped. Suggestions other than buy a Manley jumbo Shrimp are appreciated. Thanks.
For years, I ran a transformer-based Sonic Euphoria passive line stage. I wanted to try a tubed line stage, and a friend had gotten the Grounded Grid, which sounded very good to me.

So, I ordered the kit, along with a Goldpoint stepped attenuator and Bent Audio remote volume control. I used mil-spec silver hook-up wire, and built flavor 2 power cord from Chris Van Hul.

I listened to the unit like this for a while, and on the advice of a friend, I installed Clarity Caps output caps, and NOS Amperex 12AU7 tubes.

Now, the Grounded Grid never disappoints. It is extremely quiet, yet dynamic and transparent. I don't feel I'm missing anything by not having an uber-expensive preamplifier.

I'd try working on the GG a bit, I'm sure it's got more to give, with just a few relativly inexpensive upgrades.

Best of luck,regards,
I have one. Because it uses feedback tube rolling does not make as large a difference as in preamps that don't use feedback. The original output coupling caps are not very ambitious and that is a great place to start tweeking.

Another option is increasing the feedback which only entails changing a resistor.
Thank you for your insightful remarks.
A component like this is built to a certain targeted price point. As a result, the cost of parts have to be closely watched. As has been mentioned above by Dan I believe higher-quality coupling capacitors would result in much bang for the buck. Get the best caps you can afford, coupling caps do matter greatly. Good luck.