Old topic, but I thought my experience on this problem might still be of use to others. First - yes, it is a gas filled bulb running at 120 VAC or so, depends on your line voltage. So, an LED, as it's wired won't work. I still wanted a nice bright BLUE led. I happened to have a few around, so I used a USB charging adapter, such as used for most of our phones, I wired in a dropping resistor to both limit current, and drop the voltage from the 5 VDC to around 3 VDC(I think I used a 220 ohm resistor?), and then being a manly kind of man, I drilled a hole just above the on/off switch that made the led a push fit from behind. I wired the AC input on the USB adapter to the 2 bottom push on terminals that were originally mounted to the power switch and slightly widened the terminal clips so they'd push onto the AC in on the adapter.
Mounted my super bright blue led, used a little adhesive to make sure it didn't fall loose. I also used a drop or 2 of adhesive to make sure the USB adapter was secure inside the chassis too.
It looks factory, if the factory had used a panel mounted led, which they should have anyway. Once again, I'm able to SEE that it's on, which cuts back on unfortunate accidents where you turn on a preamp, etc. when the amplifier is on first. That often results in a loud PoP/Thump and maybe a hum while smoke begins to billow from your power amp. Not pretty. I speak from sad experience!
Outside of the cosmetic cost cutting, these remain terrific amplifiers. I have the A250, and it blows away some much more talked about and well regarded power amplifiers. It's dead quiet! It has uncanny channel separation too. I noted on a generic schematic I downloaded for the base design(Acurus A150 through A250) that the transformer had separate windings for each channel, not a common rail. It handles Magnepan MG 3.6r speakers with apparent ease. Just for the heck of it, I installed some nice brushed aluminum handles on the front(RAF from DigiKey) and 4 better feet too. It's such a simple design, it should last for many more years.
Very few electrolytic capacitors, and the two man PS capacitors are readily available. I think I'll keep a pair on hand, just in case some hum starts to sneak in down the road.
