I landed a couple of classic Marantz amps. The 510M has already arrived and is non-op as advertised. It powers up and hums through the speakers. The good news is the transformer does not hum and the speaker relay engages. So, the 510M is likely fixable in the hands of my extremely capable tech. I went ahead and bought a 510 (non-meter) amp just in case I need parts. Incredibly, the 510's market value is more than $1,000 less than the 510M, which sells for $1,500 and up.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...em=130285264249
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...em=120371460442

Sam,

What are the big differences with these models? What makes the "M" more desireable?

The M stands for Meter but otherwise, the 510 and 510M are identical. The fourth knob on the 510M is to adjust the meter range. IMO, the 510 looks a little ungainly with the black dial that displays only the channel PEAK indicator lights. The meters make the 510M at least twice as valuable. Go figure!

My broken 510M has been repaired and is singing beautifullly. It needed one main filter cap, so I went ahead and had both replaced. The relpacements are Mallory computer grade and are blue to match to meters. This amp tested at 288 watts per side!

288wpc per side is pretty impressive!!!!!

I thought the non "M" version was just a real dark faceplate- didn't realize it was meterless.



Tthe Soundcraftsmen amps, as you know, utilize a different all-metal faceplate when they take out the meters- and either go with a solid faceplate with a blank of LED meters or a solid faceplate and no meters.



This is definitely a corner-cutting measure and I agree it's a homely approach without meters.





However the amp must sound brutally stunning and that's some impressive power!

Internal build quality is one that deserves the term "macho" for sure.

The build is robust. The transformer is huge making the compact Amplifier Cooling Tunnel a necessity. I have to admit, the 510M is one of the nicer 250 watt class amps I've heard.

Sweet. Great gamble on the "M." Happy to hear it paid off. I need to get a 250+ watter one of these days.