Can Music Reference MR9 drive Tannoy DMT 215 II

Very high sensitivity speakers (like yours) will easily reproduce ANY noise present in your system. Tube amps and preamps generally have some hiss present and occasionally some hum too. You might try lifting the ground with a cheater plug on the amp just as an experiment but it sounds like the hum is low in level and normal given your mix of equipment. If it's not too intrusive I wouldn't worry about it. The other speakers you were using were not likely as efficient as your current set which is why you didn't hear the hum.

This is a question that I am surprised is even being asked, the answer being so obvious and such....

Shakey

I would be surprised if the RM-9 were the source of the noise but as previously mentioned the sensitivity of your speakers will let more noise through. An easy test is to get a set of shorting plugs and put them on the inputs of the amp. Then turn it on and listen for any noise at the speaker. If no noise or the noise you currently hear is reduced then the problem is elsewhere. Another thing, if you are using unshielded cables on the amp due to where the inputs st so close to the transformers they may be picking up some noise. Roger recommends shielded cables and a bit extra length that allows you to move the cables away from the transformers.

The op posted this because 150 - 500 watts is Tannoys recommendation. Those speakers are amazing. They will take anything and everything you can throw at them.

Hi Kinhoang: The tweeter should be at ear level when you are in your listening chair. My custom Sound Anchor stands are adjustable. Some of the bass boominess is sure to disappear after you lift the speakers off the floor. But you may still have to deal with acoustical null and peak room modes by, e.g., using wall treatments. I put treatments on the walls and ceiling. Also, play around with the low-frequency window settings in the crossover.

My electronics are quiet, but I have had noisy preamps in the past; and intermittent buzzing from a tube that was going bad. Make sure your tubes are quiet. And use hub- or star-grounding (both terms have the same meaning) with everything plugged into a central hub, and only one grounded plug going from hub into wall outlet.

Good luck