Herron VTPH-2A phono preamp owner's advice.

I also own the VTPH2 (not the "a") and have had it for several years. It is a fantastic phono stage and better than anything else I have used in recent years, including the Moon 310LP and the Fosgate Signature v2. Very neutral, detailed, revealing and with plenty of PRAT.

I just packed all my Naim gear for service/upgrades, so I thought to contact Keith about what is changed in the "a." He plans to call me tomorrow to discuss upgrading my unit to "a" spec. When I bought it originally, he personally delivered and set it up in my system (he lives/works a few miles away).

@dwette Do it. Get the "A" upgrade. The differences are NOT subtle.

I also live close, not as close as you (other side of the river).  Keith has been an asset to my listening enjoyment for over 20 years.

@bpoletti Done. I got the VTPH-2a back last week. Keith was reasonable on price and fast on turnaround.

What are you using for tubes? I had been using Genelex Gold Lions, but after the upgrade I decided to restore the original tunes Keith supplied. It turns out the AX7s are bad so I got a set of Electro-Harmonix AX7 for 1/3 that Keith suggested work well. I have his original AT7s in 2/4/5, but thinking about rolling for a warmer sound maybe (Mullard 4024, ?). I'm using a Clearaudio Concerto V2 cartridge, currently loaded at 47K.
Meanwhile, I'll leave the tubes I have in as is for a while. Everything needs to break in again first. My Naim 282/HCDR/250DR all went through DR upgrades and re-cap service, so it all needs to break in again.

@dwette 

I use only the tubes provided by Keith.  I have not found the need to use anything different.  I keep in touch with Keith and he lets me know if he has found something better.  I get my VTPH-2a to him for the change. When he works on a unit, it includes a listening session to make sure all is OK. 

I have never even had the case open for a look.

@bpoletti thank you for the feedback. 
Keith also encourages me to keep them as is, at least until the unit is broken in [again] (I agree with that). Sometimes I like to try different things, then I settle on something and usually do nothing else to my system for years.