I have used both 300B and 211 amps in my system. If you are going to use the Aerius at 89dB senstivity, I don't think the 300B will feel your needs. While I found the 300B best with vocals and small group jazz you probably need more power. I currently have 211 mono blocks with 91 dB senstivity speakers and it works quite well. The 211 puts out about 50 watts in my amps and should be enough for 89dB speakers. Of course there is always a loss in the bass and the top end sometimes may be a little rolled off but the midrange is what single-ended triodes are all about. Very musical. You can find new 211 tubes made in China and NOS available,but the NOS can be quite expensive.Good luck
300B,811,211 SE triodes
Hi, the said tubes each have different sonic character. Read that 300B gives best vocals but lacks the bottom & top extensions. Not familiar with 811 or 211 except their higher power outputs. I intend to build a class A SE poweramp, preferably with single output tube. Speakers are Martin Logan Aerius of 89dB efficiency. Music preference is full range Jazz instruments & vocals. Please post your experience.