340 watts peak? That is a kind of meaningless figure. What is the watts RMS? Peak watts vary widely and are not a good example of how loud an amp will go, but rather how much current it can dissipate into a load for a very brief (half cycle) period of time.
I'd wager this is a 30watt amp that can produce 340 watts for one half cycle of a 100hz waveform.
Also got to point out that Signal-to-noise ratio: 65 dB, is horrible. That is worse than cheap cassette tape without noise reduction.