I have played with outboard sets with a previous setup and the Hashimoto HM-7 based sut sounded amazing. The only thing I did not like about it is that it tended to make images very large, which for me makes the whole presentation less realistic. I know some people love big upfront images but I don't. Other than that the HM7 was clearly superior to my mc stage ... Can't even remember which photo it was.
My current preamp is a custom built David Berning all tube unit. It was originally built for Chris at Artisan Fidelity and I got hold of it a few years ago. It sounds absolutely fantastic and I'm probably an idiot for even thinking of replacing it. But I love shindo and a few years ago owned a Montrachet amplifier, which was one of the most musically compelling pieces of equipment I've ever owned. I would probably still have it except that it did not play well with my quads. The impedance was just no good for the Montrachet, and may have even damaged it if I had kept playing it! Of course I've moved on from those speakers since. So shindo has always had a great place in my heart and I know their preamps are supposed to be just wonderful. So my plan is to try one and if it does not beat the Berning, I will re-sell it. This is also one reason I need to buy used.
Yea I love my v4 amps. I run them with KT-150 tubes, even though they are the early versions, not the KT-150-optimized ones. Formerly an el-34 fan, I have been converted to the KT-150. It mates a great midrange with bigger dynamics and a bit more frequency range. And not crazy nos tube prices. I save my nos crazy for input tubes ;)