ARC REF 5SE, CJ GAT or ?

I looked into both of these to replace my Wyetech Opal, and chose the VTL 7.5 Mk iii. Astonishing neutrality, imaging and soundstanging; great remote; and exceptional flexibility (RCA and XLR, among many other features). If you find one used (and they are rare as hen's teeth, which should tell you something), I would grab it. You will be happy.

BTW, I use the VTL 7.5 iii with a Krell FPB 300cx, so if you were wondering about compatibility with Krell, there it is.

Neal

The Krell(s) tend to be more analytical with great bottom end extension. I would look for a pre amp with more warmth. At your price point you pretty much can choose anything you want, so I wouldn't be too hasty about a choice but would try several tube units before making an important decision for your system.

An exception to this would be to try a comparable Krell pre amp just to see what synergies may exist given that the Krell designers probably used their own products for final testing before releasing the amp to the public.

If you can live with the GAT's single ended RCA connections, I vote GAT. I've looked at and owned other preamps but have always been the happiest with my GAT. Great 3D and layering with an ever so slightly sweet top end with great width and height. I love it. Also, only two tubes to replace and relatively inexpensive to re-tube. At the prices for the used GATs right now, I think they are a bargain.