Hi dhcod...
6moons audio reviews: Music Reference RM-10 MkII
If you can find one of these at a fair price, you won't be disappointed. The "sweetness" of the 300B midrange may give way to overall honesty of the EL84's sound. I have taken mine to a much more refined level by a full Marigo Tuning Dot application and upgrading to a full complement of "Tom Evan's recommended," Harma Watford Valves. Not being a "just for fun" tube roller, I went through 3 sets (Mullard, JJ &Sovtek) before finding my flavor. The RM-10 features point to point wiring (no board) for reliability & longevity. A great set of tubes can easily be had for under $200.
Another possibility...if you just love what your monitors give you, as I do, you might try rolling off the deep bass to them, say at 80Hz to a sub or pair of subs, keeping the 300B amp. In my room, removing the deep bass from my Revolution Be monitors allow them to fully blossom and achieve above 90db decibels, without strain.
More Peace in 2023 Pin