Switch preamp?

 I use to have an older Krell 200 FPB stereo amp.  When I added a tube pre, I had to open the amp up and remove a small jumper(manual switch) connector.  Something about tubes damaging the amp.  The information was in the manual but the location was not so I called Krell and I performed the job with the tech over the phone.

Despite Krell's remonstrations this bit about tubes damaging the amp is a myth. Its based entirely on a single customer's preamp having a failed coupling capacitor; which is the sort of thing that can blow up an amp whether the preamp is tube or solid state!

Regarding the ability of tubes to drive ESLs and Martin Logans in particular:

The issue is that of impedance- Martin Logan makes ESLs (which normally work best with tubes) but to try to get better solid state compatibility (and thus a larger market) they keep their impedances down. The typical Martin Logan is 4 ohms in the bass and 0.7 ohms at 20KHz.

You can correct this with a set of ZEROs (www.zeroimpedance.com) and then a wide variety of tube amps could be used. Of course, many tube amps will work with this speaker if you use the 4 ohm tap even without the ZEROs.

notesaddict
 I am happy with the sound but ...

Sounds like audiophilosis. I have it too. My system sounds better now than ever before. Yet I keep looking at tonearms and lately, tube  amps. Before that tube preamps. I can give good reasons for wanting to change. My tonearm  (OL Illustrious) was suppose to be temporary til I could get better. That was 7 yrs ago. My amp & preamp are opposite of the audiophile standard. Tube amp and SS preamp. Never mind the preamp is a Stereophile class A (CJ PFR)....its old too. My amp is too cheap to be audiophile approved  (Bob Latino ST-70). But it replaced a $4k SS amp and put it to shame. I have a feeling that despite the system sounding fantastic now, I'm going to change something. So far all my changes have been for the best. But the odds are against me at this point. Surely I'll make a change at some point which will destroy every bit of the synergy in my system. Even though I know this, I keep looking.  
FWIW, I like CJ gear. I'd also consider the Primaluna.  Also, Don Sachs makes a tube Preamp which gets rave reviews by its owners. He also makes a KT-88 Tube amp which he claims is better than the Citation 2 amps he rebuilds for Jim McShane. Both will cost you a little over the $5k budget. He may even give you a short audition period. He is very personable and easy to talk too
Also, Bob Latino makes an M 125 Tube mono blocks which get very good reviews and are about $2800 with tubes. Again, great sound and Bob builds a good product and is very good with customer service.
Good luck with whatever direction you go.

Artemus, yes, a case of the perpetual audiophilosis with diminishing returns. I perused Sach's comprehensive website; compelling. I am going to give him a call. Thank you.

Artemus, I communicated with Don as suggested and just made a deposit on a preamp that should be ready in 12 weeks. 

notesaddict. Glad I could help.  It sounds like Don is quite backed up. Did he offer you an audition period? From my remembrance he uses top quality parts in his amps and preamps. I probably should have bought one of his preamps last year when I talked to him. I believe he has raised his prices since then though I believe he has upgraded some parts he uses since I talked to him.
Please keep us posted on your impressions of the preamp after you get it.