Which amp will cause a larger increase in electric bill?


Threshold SA/4e or Threshold S500 II?  How to determine?  I cant find idle draw on SA/4e.

Thanks.
128x128jpainter236
In general, if it is solid state, I would not worry about power consumption or your electric bill.   It doesn't matter if it is Class D or Class AB.   Granted Class A amps do consume some power when it is on and idling but most Class A amplifiers are not pure Class A over their entire power range.  If you do spring for pure Class A, do ask the manufacturer what the idle current is like, as they have to deal with that power in a big, expensive way.  These days, I suspect even the pure Class A guys turn their bias down during long idle periods. 

If it is a vacuum tube amp, then yeah, you will definitely see it on your bill.  Big time.   In a big way.   Trust me on this.  If you doubt me, just ask my checkbook!  My system burns up about 1000 Watts when idling, so I turn it off when not in use. 

There are some new regulations on idle power consumption when the equipment is plugged in but not in use.   I believe the power level is under 1W now, about a half Watt or so;  I know it has been dropping over the last decade.  

That being said, I would not leave your equipment on 24/7 unless you make a point of playing it every single day.   In that case, perhaps leaving it on would make more sense.   Although for vacuum tubes, that may not be the case.   Some tubes have finite life times regardless if they are playing music or not.  Simply being on is burning up lifespan.  Again, check with the manufacturer. 
I don't believe those are close to current Class A amps and they probably do draw a lot of current on idle.  They are the least efficient of all amps.  I had an Odyssey Stratos extreme class AB amp for 5 years which cost about 30.00 a month to run as they are designed to be on all the time.  My electric bill went down that amount after selling it and going with something else.
Class A amps draw approximately 5 times their rated power at idle (and at load). The 100 wpc SA/4e will probably draw about 1,000 watts or a kilowatt hour of electricity when it’s powered on.

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