"But Nick at Rogue recommends the RP-1 over the 99. He said the tubes are improved.
"
Heh, definitely a difference in opinion. I love Rogue Audio, and have owned several of their components (including 5 preamps: a 99 Magnum, Hera, Hera II, Athena,
RP-9), but I've never been a fan of the 12AU7 tube (as used in the RP-1/5/7). Most tube aficionados will tell you the same - and that the 6SN7 tube (as used in the 99) is far superior for similar roles. One knock against the 99 Magnum is that (due to the configuration of its 4x 6SN7) it has a ton of ton of gain (23dB), and the lead pair of 6SN7 slots (the 2 on the right-hand side) are VERY sensitive to noise & microphony. But personally I'd still take those concerns over a 12AU7 / MOSFET hybrid preamp, especially at their entry level unit.
I always replaced the 12AU7 in their power amps with 12BH7 (beware the extra heater current draw before you do this), and got a significant improvement in sound.