New Phono Pre-Amp

I spent only slightly more than that on my used Camelot Technology Lancelot, which Fremer rated above the others mentioned FWIW (it sells for about $900-$1K new). It's battery-powered BTW, something which I suspect is a very canny design choice for a phonostage, and permits relatively easy loading- and gain-resistor swaps. It also sounds great, to me. Somewhat unwieldy physically however (2-chassis, though not too large), and it ain't exactly beautiful to behold. Excellent supportive company to deal with concerning any eventualities, and made in USA.

If you look long and hard enough, you might find the EAR 834P at that price...it's a cut above the units mentioned thus far, and has that "tube magic".

Another option is the Monolithic PS-1 w/ the outboard power supply, the HC-1. I've seen this combo for sale here on Audiogon for 400$. Hard to beat at this price point. While I haven't personally compared this combo with the Black Cube, a number of reviewers claim the Monolithic combo is superior.

I bought a Monolithic PS1 with power supply and it has been wonderful with my MMF-7. I wanted to keep the price in perspective and it is a good place to start. Happy listening :-)

I'm going to second the recommendation for an EAR 834P. If you can afford to stretch your budget to around $600-650 you will be stepping into another league. I've been using one of these for some time now and you cannot beat it for for anywhere near its price. A high-end product that is suitable for very high resolution systems. You have to step up to something like an Audio Research PH3 in beat it. By the way, it is rare, but I've seen these on Audiogon for around $500-550. They go fast at that price though. Good luck and take your time.