Havent heard those names in a long time.
The SinglePower would most likely blow a hole in the 900, if it didn't burn the house down first. Since Mikhail disappeared some years ago probably not a great investment.
Don't have a lot to say about the Dynahi maybe someone else can chime in. These are some definite "old skool" amps youre considering.
My SinglePower is rebuilt so its totally safe for operation and it sounds great.