First...welcome to a hobby that promises a lifetime of enjoyment!
As you've already discovered, MMGs need some juice to sound their best; I'd look for an NAD C370 - should be able to find one for less that your stated budget. Many of us started with NAD gear and many of us still use NAD gear! See online reviews. The sound is not exactly "tube-like" but very enjoyable nonetheless.
Pros: plenty of power to drive the MMGs, pre-out/amp-in to enable future incremental upgrades, built-in headphone amp, remote, quality construction, good value and...it sounds great!