1970's Mordaunt Short MS 400's Spec/What Amp?

[RobertsK]

I have these two lovely Mordaunt Short MS400's but have no idea what amplifier to use with them. I have used a SONY STR-DE405 previously but it ran with some problems often only powering one speaker unless I gave the amp a little hit on the side and also cutting out flashing up with the words 'Protect' on the Amplifier screen.

Trouble is I literally have no idea how many Ohm's these speakers are or any other spec as the only info on them is the model number and serial number and thus do not know what amplifier to get to run them.

Any help/comments at all are VERY VERY appreciated on something that I have been trying to figure out for well over a year. Images of Speakers below if I've done the links right

Thanks,

Kharn

[SCALEXCENTRIC]

Kef version - which appears to be the one you have is 8 ohms with a handling capacity of 35 watts.
Select a decent quality amplifier with low distortion to match this output. These speakers will show up a cheap amplifier as they were and if in good condition remain a high quality product with great mids and highs to 25kHz and a natural sounding bass down to 35 Hz. Great for vocals jazz and classical music.
Avoid overpowering the Coles tweeters - although available they are becoming expensive.
Might be worth checking solder connections of your speaker wires and the crossovers capacitors to make sure all is ok.