VAC Phono in Avatar Super

I have a VAC Avatar Super with a phono stage that has 42 db of gain. I have a Benz Glider High Output cartridge at 2.5mV. The documentation says it is appropriate with phono stages with gain of 40db or more and I asked VAC about it before I purchased. I have to use more volume than with my CDP and at higher volumes there is a background hum that is noticeable in quiet passages. VAC sells an external MC step-up network that plugs into the MM input that I think is like $900. Given that I have a high output cart, would the VAC step-up be a mismatch? Would I be better off going with a seperate phono stage? Different cartridge? Any and all advice appreciated.
The VAC step up is $600. Have you tested the phono tubes? Could possibly have a noisy tube in the phono stage.

If the tube is not the problem, the step up would probably lower the noise floor.

A step up would provide too much gain.
Suggest John's guidance be followed, or contact VAC.
Divo's probably right (unless this stepup is only 5db or so).

A stepup would also lower the impedance seen by the cartridge. Tonal balance might be significantly altered, yielding reduced HF's and/or heavier bass.
Dear Maineiac: +++++ " Given that I have a high output cart, would the VAC step-up be a mismatch? " +++++

Any step-up transformer is a mismatch for the quality sound reproduction on any preamp: always do a degradation to the signal.

As a fact your VAC was designed more for MM cartridges than for HO MC ones.
Now, out there there are several great MM cartridges that outperform the cartridge that you own ( for less dollars ) and many others MC top " names ". Look for: Goldring, Ortofon, Audio Technica, Shure, Music maker, Clearaudio, etc, etc.

I can asure you that you will be really happy with the MM cartridge.

Regards and enjoy the music.
Hello Maineiac,
You are not alone! I too own an Avatar Super and I have been working on clearing the problem with mine.
I have changed tubes with little or no success.
I was told it was my Grado wood cartridge, that it had too much gain @ 5 mv, so bought a new Clearaudio Virtuoso Wood. It was a little better but still not even close to acceptable.
I rewired my tone arm with the Incognito kit. The problem worsened. That was when I discovered that the hum changed depending where I grounded the arm to the Avatar chassis.
Now feeling less than intelligent I call VAC and talk to them about the hum in a nutshell they told me to ground it wherever it works. I have mine grounded to the ground on the right channel RCA. VAC's own external MC set-up grounds through this contact. This worked for me, although I find it to be a little Mickey Mouse, it works and sounds fabulous! Good Luck!
I don't think it is ground hum I am hearing, it is background noise from having the volume up to compensate for the low output of the cartridge (2.5). I have mine grounded to the ground screw next to the phone input. It would be nice to have just a little more gain I think. I am thinking of messing with some MM carts as suggested above just to see what happens. I would love to know how the Vac's phono stage stacks up against some of the well known brands out there.
I would love to know how the Vac's phono stage stacks up against some of the well known brands out there.

I have demoed the VAC Renaissance (full-function preamp) in my system. I don't know how close the Avatar comes to that, but the Renaissance does include internal stepups on the MC inputs, so their topologies seem similar. The Renaissance is higher up the food chain of course, so take it FWIW.

In my system the Renaissance easily bested the Aesthetix Rhea/Calypso and its line stage easily bested a Lamm line stage. It was, in fact, the second best preamp I've heard. My Nick Doshi Alaap had slightly better frequency extension at both ends and was slightly clearer on digital sources, but the differences were not large. If I didn't have one of Nick's units the Renaissance would be my choice from all the commercial preamps I've heard.
Thanks for your input Doug. Mine sounds good but I don't have anything to compare it to. According to the VAC web-site, the Vac Avatar Super has a triode MM phono stage derived from the VAC Signature Preamplifier and Renaissance grade parts throughout.
Maineiac, if you want to set up an A/B experiment let me know. I don't think we're that far apart. I can promise good times and good tunes!

2.5mv should be plenty for this moving magnet phono stage. I have used cartridges with 1.5mv into phono stages with similar gain without excessive noise or the need to turn the volume way up. Something is wrong with the phono stage, grounding scheme or the cartridge(open loop?). Don't get the step-up device, it's not needed. Even the lowest step-up device at 1:5(most are 1:10 or 1:12) would present the phono stage with 12.5 mv which would overload any normally functioning phonostage. I would start with a phone call to VAC. Let us know what happens.