The Herron VTPH-2A is an excellent unit - we did an A/B against the Vendetta SCP2-D in my main system and it was pretty much a tie. Now discontinued, but a lot easier to find than another John Curl Vendetta.
I also use a Conrad Johnson Premier 15 which is a good performer and you can find a new one for a lot less than the new price of $4K they originally sold for.