Arkless Electronics
Trade: Amp design and repairs.
I Must disagree - I have not heard a pair for more than 30 years, but when traveling in Australia I worked in a HiFi Store in Bondi Junction - their best speakers were LS3/5as, especially matched with a top of the line NEC CDP (Never seen one since, stunning build and sound). Sounded great with all the shops amps, from lowly Nads and Rotels up to top of the line Japanese and Linn amps.
One day we sneaked the speakers and CDP to another store with a Musical Fidelity big **** off power amp (450? Huge black box with blue lettering ). First listened to NEC CDP with MF and their AE1s on those big stands, stunning. Then replaced the AEs with the LS3/5as - best sound I ever heard except for some SF Extrema’s powered by the same SE valve hybrid amps I have now(except for my current ESL63s of course ). LS3/5a with a bit of current into them sound stunning IMO but, yes, they sound good with almost anything.
Probably an A370. Blue lettering says MkII. no such thing as 450 and only very few SA470's were made. As always it has absolutely nothing to do with current or power. It's just a very good sounding amplifier.