Upgrading Tube Preamp from Audio Research LS-7 - Recommendations for better soundstage?

I want to replace my ARC LS-7 tube preamp. I fell in love with the bloom and warmth when I bought it. But it doesn't have the soundstage focus or width that I had heard from others I had demo'd at the time. I think I want both now!

Any recommendations on upgrades? - tube for sure, but something with better soundstaging - more focus and width. Open to used gear like an ARC SP-16L or Prima Luna Prologue or Conrad Johnson Classic or PV15 or Rogue 99 or??? These are just some I had seen used in the $1000 - $1500 range which is basically my budget.

Don't need a phono amp but would use one, don't need a remote but would use one.

My system.
- Digital and vinyl sources
- ARC LS-7 Tube preamp
- McCormack DNA-1 solid state amp
- Martin Logan SL3 Electrostat/dynamic woofer

Thanks much.

Audio Note M2 preamp, about $1500 used. Uses 6SN7 in the gain stage, tube rectifier and regulator.
Music is realistic with a wide and deep soundstage.

LS 25 or 26? Similar ARC house sound with a single gain stage and cathode follower with no feedback. The 25 mk2 and 26 are especially quiet but if you have a stash of 6922s then a 25 Mk1 is an option. The 26 has good stage width. Also really nice if you're planning on going balanced in the future.
Just a thought.
Good hunting.
There’s a Linear Tube Audio MicroZOTL MZ2 with external linear power supply and other extras for sale on US Audio Mart for $1500 that might be further negotiable.  Read the Positive Feedback and Part Time Audiophile reviews — soundstaging is definitely a strength.  Best of luck.  
Had a LS7 when it first came out and didn’t keep it long as I preferred my next pre, a Sonic Frontiers SFL1 over it with Mullard tube. I felt the SF was a more musical preamp but that’s just my opinion. Later I picked up a ModWright SWL 9.0 SE and very much enjoyed it but later had the bug to search for better and took home a ARC LS25 MKII and felt the ModWright at least in my system was more musical where I felt the ARC was a little on the cold side, not bad but didn’t excite me. Finally I settled on a ModWright LS36.5 and I’m pretty sure this will be my last preamp. If you’re looking in the $1,500 range I’d suggest reading up on the ModWright SWL 9.0 SE or find the current Anniversary model. It’s a great preamp and even though it’s been years since I’ve listened to an LS7 I’m pretty sure it’s safe to say the ModWright is a far better preamp. Forgot to mentioned I tried NOS on the LS7 and still felt even the Sonic Frontier was much better and the ModWright being far better.