BAT VK 53SE vs ARC Ref 5SE

Do you know how sensitive those amps are?  SETs tend to be very sensitive and work best with very little to no gain.  They are also not balanced circuits, given the name "single ended triode".  Do your Welborne's have XLR inputs?  That would be odd. If they do, they are using a transformers to convert a balanced signal to unbalanced for amplification.  Are they mono's or is it a stereo amp?

With those Duo Mezzo, maybe this was different previously, but the current model you have a choice between using just the speaker level inputs or running cables from the preamp.  I don't even understand why the XLR option exists as it is usually much more appealing to use speaker level inputs.  This ensures the same signal is reaching all drivers at precisely the same time.  There are timing mods to that bass unit but this typically requires more not less adjustment.  Are you having an issue with noise in the bass module?  Why do you want to run an XLR to it?

Both of those preamps are fully balanced and tend to excel in fully balanced systems.  They would be very low on my list to pair with a SET.  They both have a reputation for being very quiet so I get why they are conceptually appealing.  I guess the ARC has to be the better choice since it actually has single ended outputs to send to your amp(s).  The BAT only has XLR outputs and would be a poor choice. 

Help me understand what the issue is and why you want to make a change.  I would very much like to make sure this is solving your problem.  

Incidentally, I am an Avantgarde dealer and I import a line of SETs so I am pretty familiar with this space.  

Hi richcam, 
I would have expected the 43se all solid state pre (or did you mean the 33se which is a tube unit) to at least equal the 53se in the low end being all solid state. I am using a 50se with real supertubes and thought the 43se would give me more punch. Sounds like the 53se is much better all over. Please clarify for me.

During my quest for a high quality sounding preamp, I auditioned 6 preamps one of which was the ARC Ref 5SE. I was able to settle on the BAT VK53SE  to go with a Bryston 4BSST2 amp which I've now upgraded to BAT VK255se monos.
I tried the lower end model BAT VK43SE for about a month from Music Direct with the 6, 6h30 tubes and I thought it was very musical but it lacked low end bass punch and had a smaller sound stage. A local dealer was able to let me borrow the ARC Ref 5se preamp that you asked about. It's slightly larger than the BAT and burns MUCH hotter because it uses a 6550 and 1 6H30 tube for it's power supply. I have to use my components in a wooden built in cabinet, a major pain when trying to change components and wires. So guess what? the ARC uses a plastic top grill and would have melted without proper ventilation. WTF plastic?? The build quality on the BAT is much better, no plastic and the performace?? Well let's just say holy cow!!! I could only guess how the Rex would be with a separate power supply. BTW, the BAT VK53se is upgradable to the REX.The ARC Ref 5se doesn't compare. I know with the Ref 6 ARC has made some rather noticeable improvements. I did like the tube usage indicator on the ARC however.
One of the other pre amps I really liked, especially for the money, was the John Curl designed Parasound JC2 BP at about one quarter of the original price of the BAT or the ARC.

hk_fan also nails it. The 6H30 tube is like a transistor and yet in my experiences even worse than some transistors for even a MOSFET has some life in it compared to the 6H30. Truly, with some excellent new re-released tubes out there plus several good sources of NOS tubes (not Ebay) one can find an excellent preamp that will allow you to experience what tubes can really do for a music system.
I hope that helps and it does not appear that I am beating the dead horse here.

Agree with @zkidd .  The 6H30 is a tube that sounds like a transistor to my ear.  I think it's for those who want transistor like attributes but still like saying they are a "tube person".

@zkidd +10    I could not have said it better!

Unless I have missed my hunch here both units use the "Super Tube", which is the 6H-30 tube I believe.  As someone who has owned over 30 preamps (yep, I am OCD in this area and I know it) I have a pretty good idea of tubes, and tube amps, plus I own over 800 NOS tubes. I have owned a lot of ARC preamps as well as BAT, and the BAT preamps from the early days where the 6922 was used as well as some 5881 or 6V6 tubes as rectifiers or in the power supply, those were fine preamps. I have owned two BAT preamps with the Super-Tube and sold them to get back to preamps with the 6922 and I could roll tubes that help bring out the best in the BAT. 
Of course, there are those who will say I am nuts, or I cannot hear, or my head has been relocated to another area on my body (or in my body) but I have never, EVER been happy with the 6H30.
There are some great preamps out there with some good NOS tubes so is there any particular reason for those two preamps? As always, it is all so system dependent ...