If the music sounds like it is stuck in a box, then something is either wrong with your setup or broken. I had a first generation Freya that I purchased and it was definitely defective, it sounded extremely veiled and I returned it. I subsequently purchased a Freya S which worked perfectly. If it were me, I would proceed as follows:
1) Confirm all your equipment is working properly. The Cenepro amps, while not audio jewelry, were well designed and should have plenty of power and sound good with your speaker.
2) Take a look at your room setup. Is your room heavily dampened. Do you have the speakers positioned well (have you tried moving them around?)?
3) Get a Umik and REW (less than $100) and measure your setup. That will tell if there is anything really wrong with your equipment and help identify potential room issues.
4) As far as the hiss, how loud? Is it only when you are up against the speakers with the volume turned up? Is it there when the preamp is unplugged from the amp? Louder or quieter when you disconnect the preamp?
Going back to your original question, there are no actual third party measurements I have ever seen of the Magtech amp. What I can tell you is that Roger Sanders claims that you need different types of amps for electrostatic and planar speakers and dynamic speakers have no basis in fact, as are his different $600 speaker cables. An amplifier puts out a set voltage in response to an input signal up to its maximum rated output. The amount of current the amplifier supplies to a speaker is the amount needed to maintain the voltage into the specific impedance plus any phase angle. If there isn't enough current, voltage will sag. That is Ohm's law, no ifs, ands or buts.
I would not suggest you spend $11,000 on a pair of Magetechs or even $5,500 on a stereo model. If you want to spend a lot on amps, buy the Benchmarks and run them mono. They will drive your Revels, another member here has a pair and spoke to Benchmark and they said they will comfortably drive them in mono. Alternatively, do what the other member here ended up doing, buy a pair of March Audio P701 amps (Hypex NC1200) for $2,700, 400 watt into 8 ohms, 700 into 4 and 1200 into 2 ohms. March Audio will also sell you cables, but his are about $125 a pair and don't come with $500 of bullc*ap claims.