I’ve owned both in the past but not used them together. Both are great sounding pieces, particularly the A21, and not at all analytical or harsh. BUT if you can score a used Rogue Athena or Hera (if a great deal) preamp it will sound much better yet than any 99, even super-magnum’d. Then you can also get off the trail-of-tears that is finding good sounding NOS 6sn7 tubes that are also quiet enough and don’t cost a fortune. And I wouldn’t bother with entry-level Rogue preamps like Metis or RP-1.
The issue with some Rogue preamps will be noise due to their high gain (the 99 has 23dB which is a LOT), but fortunately that A21 has adjustable gain controls to perfectly counteract this - so it should be a good match.
The only Benchmark gear I've heard is the old DAC-1, way back in 2000s when it was being hyped as possibly the best DAC ever. I thought it sounded dry and analytical, somehow boring and grating at the same time. The A21 with a good tube pre will definitely NOT be like that at all.
The issue with some Rogue preamps will be noise due to their high gain (the 99 has 23dB which is a LOT), but fortunately that A21 has adjustable gain controls to perfectly counteract this - so it should be a good match.
The only Benchmark gear I've heard is the old DAC-1, way back in 2000s when it was being hyped as possibly the best DAC ever. I thought it sounded dry and analytical, somehow boring and grating at the same time. The A21 with a good tube pre will definitely NOT be like that at all.