Crisp sounding tubes for Modwright 5400ES

Hey guys, really appreciate all your help here. It looks like the first thing I should try is to swop out the Mullard 5AR4; then maybe try some other output tubes, maybe the GEs.
As for my cables, I'm using a Lessloss DFPC power cord for the 5400ES, and a Black Sand Silver Mk V for the power supply. From the power cable forums, it does not seem like these cables would cause my problem. As for ICs, I have tried Pure Note Vanguard and VH Audio fine silver DIY ICs. The latter helps to bring to lift the top end a touch.
In case any of you are interested, the rest of my system is Aesthetix Calypso pre-amp; Krell FPB300c power and Von Schweikert VR4jr speakers. I use a Hydra 8 power conditioner and a separate Hydra 2 for the Krell. I also take a lot of care in component a lot of care taken in system set-up with use of Herbie's accessories equipment & speaker support with accessories from Herbie's Lab.
Thanks again.

Wig, Yes, please do let us know. I will be interested to know if you also prefer the Synergy to the vintage Mullard in the ModWright. By the way, what year production Mullard do you have? Mine was 1969.

Brownsfan,

I believe mine are early 1960

Podeschi is spot on with his power cord observation on the MW. Audience PC produces a quieter background and allows you to listen deeper into the soundstage. Other cables were good if you want a more forward sound and less
precise localization of images.

Audience just sound more natural...

I just rcvd the Create 5AR4 tube and my initial 15 min observation with my Shure 840 headphones and they are fantastic and will need 50+ hours to stabilize.

Waay more ambiance and detail retrieval, more to follow after listening through my system tonight...