Re: M30 & SHL5 output
The honest answer is 'something over 100dB at 1m' but as I've never measured the maximum sound pressure level (and respect my ears too much) I can't be precise.
Not only that, tere are many factors which must be taken into account to give a meaningful number such as ....
a) how far away is the microphone?
b) are both speakers playing exactly the same (mono) signal?
c) is the signal bandwidth-limited so that, for example, all deep bass and extreme HF are eliminated and do not reach the speakers?
d) are we measuring long-term maxima or just a burst, and in both cases over precisely what time period?
e) is permanent but minor damage permitted to the speakers?
Harbeth - and indeed all predecessor BBC-monitor speakers are designed to be listened to at a moderate level. You can get an idea of what I think is moderate from the Video Vault of a listening test underway.
Alan A. Shaw
Harbeth Audio UK