I have the I2A3. It's dead quiet even over 110dB compression horns. Very few cost-no-object tube amps will be. Build quality is very high and sonics are at least twice as good as the retail price and if you've got the right speakers (always a must), truly excellent. My reviewer John Potis was equally impressed with the KT88 pieces and we've reviewed Melody's amps for Genesis Loudspeakers (modified by Genesis after OEM receipt from China) which also were very good.
For the money, Melody is one of the best Chinese tube brands on the market. I couldn't tell you what is the hot product within the line but I've heard the SP9, own the little SP3 and the I2A3 and have also heard the 1688 preamp. My comments apply to all of those so it seems fair to thin that they'd apply across the line...
Make sure you get 120V product for the US, not some grey-market units intended for the HK market. Melody winds its transformer for 120, 220, 230 and 240 so you want to get the rating that corresponds to your wall outlet.