QUESTIONS ON TUBES

Suggest you don't change any tubes until you have become very familiar with the sound of your amp and your gear....then you will be able to hear "differences" when you start tube rolling. Start going to Audio Asylum and start reading and learning from other inmates...BTW there are many tube substitution books out there and the 6L6 has many "flavors."
Welcome to the tube world...predict you'll never go back to SS.
Larry

Larry gives good advice. IIRC, 6L6 equivalents include 5881.

brent has very good information on tube options and a good selection when you are ready to buy at www.audiotubes.com

There have been posts both here and on AA that there are no substitutions for the 6N1 tube. So you may be stuck with the Chinese offerings. This may also be true of the 6N2 tube as well.

FrankC

Thanks for the infomation. That helps a lot. At least I know where should I start from. By the way, regarding Frank's info, I saw some ad using 12AX7 and 12AU7 for Mingda's other model as pre-amp stage, should I try?
Once again, thanks for the answer ^_^

That, you will need to check with the manufacturer to see whether these tubes can be used. It might be the case where somebody had tweaked the circuits to accept the 12AX7/12AU7 tubes.

FrankC