Esoteric S-05 30 watt Class A Amp

Hi Agoners,

I recently bought a new/demo Esoteric S-05 class A amp. 
I have only had it for a few days, and I can’t find much online.  
I have a few questions:

1) It appears to only have 💯 on and 💯 off.  I don’t see an obvious standby mode. 
When I shut it off via the front button, does it keep any parts of it warm or is it effectively shutting it completely off?  
2) Does it need to warm up every time I turn it on?

3) I am not sure how many hours it has, but likely isn’t fully broken in.  What should I expect to hear during break in. Note: it made a massive leap forward about 10 hours or so of use.  

I hope to hear from other Esoteric owners, but thanks to everyone who may have something to share. 

Thank you! 


When I purchased a Pass Labs 250.8 Demo , Mark at Reno Hi-FI told me when I get it all hooked up leave it on for five days as it was not broken in . I did what he said and its wonderful.

According to the manual, there is a switch on the back of the amp for "auto off".  When selected, the amp will shut off when no signal has been received for 30 minutes.  My Esoteric equipment does the same.  In fact, my CD player doesn't have the option of always on.  Esoteric clearly believes leaving their equipment powered up 24/7 is not required.  Many who own SS amps believe turning them on a couple hours before a listening session is all that's needed.  An equal number believe always on is the only way to go.  Trust your own ears.  

I’m a “leave the amp on” kinda guy but even I wouldn’t do that with a full Class A (or tube) amp. Hopefully your amp doesn’t require many hours to get to its optimal operating performance, but many Class A amps unfortunately do.  If you do a lot of your listening on the weekend I’d probably leave it on for that and then turn it off Sunday night unless you find the amp to come up to sound fairly quickly.  Go by your ears.

Thanks everyone.  

@bigtwin yeah.  I did that, but it seemed to be a full off.  It took I would say 30mins to sound pretty good and 45-60 to seem fully warm.  I can live with the 20-30mins, that matches a good decanting window much of the time. ;)   60mins seems like I need to do too much planning to listen. 

@soix I left the amp on after my evening listening yesterday.  I'll keep it on for the next few days to see if there is a noticeable (and worthy) improvement in the amp by leaving it on constantly.  

From what I've ready there are three potential concerns with leaving it on. 1) Cost and (for those concerned) environmental impact, 2) heat output into the room, and 3) heat harming the amplifier overtime. 

I've ready that costs are likely less than $10/mos, so I'm not too concerned by that. 

What I would be mostly concerned with is damage to the amplifier over time.  It is well ventilated in a rack that is open on front, back, both sides, and top.  

Any other concerns I am not considering by leaving it on all the time?  And, anyone have experience with damaging the amp by doing so? 

Thanks again!

Checking in to share some observations with my "leave it on" experiment. 

At 20-hours of on time I checked in and was impressed by further transparency, texture/inner detail, a greatly reduced sibilance, and firmer bass at the expense of trade-offs. 

At 26-hours, I heard a collapsing of the soundstage - clearly a step back. This has me thinking the amp must still be breaking-in. 

I bought it as a demo and I've only had it on about 45 or so hours (last 36hrs constant on). 

I'll check in again this evening. 


Just wanted to check back in. 
The amp warms up and sounds very good at about 35 mins and I can’t make out any further improvements after about 45mins warm up. 
Leaving it on all the time does nothing for the sound for me.  It sounds the same if being off for 18 hours and warming up for only 45mins

All the observations I made above were simply the amp breaking in.