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

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.

+1 de Havilland UltraVerve 3.  I’m listening right now to my de Havilland Mercury 3.  See my review posted today of the Mercury 3 which is just the Big Brother to the UltraVerve 3.

I’m sure they share sonic characteristics.

Those are some great suggestions. Ones That weren’t on my radar. Been wanting to venture into new territory. Thank you all very much. The hunt begins. 

Have you read about the Don sachs model 2? Have you read the preamp deal of the century thread regarding the Supratek preamps? I'd add those to your list for your consideration. Both are very highly rated custom made by hand products from very small companies, So they don't get a lot of press.

Well I found a UltraVerve 3 with remote and lots of tubes to roll. Should get it Friday. Thank you everyone for your great info and tips. Truly appreciated.