I have not but I have compared many preamps to my 21A Auricap and I have always returned to the Belles. I did like a few more, the ARC Ref 3 provided a little more air, detail and was a little more musical but lost a little warmth and base, overall I like the ARC but not for several thousand more money. The same with the VTL 6.5, nice detail of the ARC, much better base, all around an improvement but at $11,500. I will be trying the new VTL 5.5 series II and would recommend trying before buying. I will look forward to seeing what you decide. PS, I found buying really nice well matched NOS tubes and stillpoints a wonderful upgrade on the belles.