How can I tell if I am overdriving the amp or the speakers?

I have a Hegel H390 driving KEF Reference 5 speakers and when I play something loud, the upper midrange ( saxophone, electric guitar, piano ) start sounding sharp and annoying. The amp is 250 x 2 into 8 ohms, stable down to 2 ohms and the speakers are 90 dbs, 8 ohm, ( min 3.2 ) 50-400 watts. I’m pretty sure it’s not room acoustics, but.




It can also be the room, or speaker/room interactions by the way.  You can experiment with blankets and pillows.  Put some around the room and see if they change that aspect of your listening.  If they do, in a positive way, consider room treatment.

The walls are an obvious choice, but I've found that some of this hash lives on the floor between and behind the speakers.

Your first clue is the sound taking a nose dive.   Becoming hard, brittle, annoying, listener fatigue, etc.   The second clue is any warning LED on your amp.   The third is blown fuses.  Your amp may not be clipping but may be current starving at some frequencies during slewing, which would cause the "sharp" sounds you are hearing.  It is hard to say but you clearly have something going on that is not right.  Note that high capacitance speaker cables can also cause this effect.   Do you have a long run of speaker cable?

start sounding sharp and annoying. 

That is your first warning. But you really should not be playing that loud. I always reduce the volume until I am at a still satisfying loudness and not overdriving the room, the equipment, or my ears. If you are running out of have to pay to play but 250 watts should really be able to do the job...however 500 wpc will do more. 

Please tell us your front end components and cabling on the front end. Also, give us an idea of speaker and listening positioning. Toe in etc… Thank you.

"The amp is 250 x 2 into 8 ohms," and the speakers are rated at 90?

I wouldn't think it would be the amp running out of power.  I would think the speakers are just trying to work to hard.  But I also think that the room acoustics suggestion has merit.  Back in the late '90s & early '00s, I was in the mode to be pretty much be playing my stuff to loud all the time (& the stuff I was using wasn't cheap stuff, either). I would be jamming out to ear bleed levels in the living room & thinking that I was at the cusp of clipping, but when I'd go out on the back porch to barbecue or whatever, everything sounded sweet & clear with no distortion.  

I don't think you are "overdriving" anything. I think you mean pushing the speakers or amp to where they start distorting.  It would get really, really loud before that happened.  some songs are recorded with too much treble/upper midrange and come across harsh on an accurate system so make sure you aren't testing with the same song every time.  Some amps are harsh.  I have a friend with the same amp hooked up to some Raidhos and he plays it very loud with no harshness.  His system sounds better than mine.   I suspect the speakers are a bit harsh.  I have a tube amp and had to swap out a few tubes to eliminate harshness but you can't do that.   --Jerry

@spatialking ,

Lets see, no warning light. No blown fuses, oh and I have AQ, 8’ Rocket 88 speaker wire.


@grannyring ,

15’ 6”x 20’ room with openings on every wall. Front end is either an Oppo, Audiolab 6000CDT or using upnp to a NAS. 8’ runs of AQ Rocket 88 wire. Speakers are 7’6” apart with my listening position at 7’6” and no toe-in.


And while I am play some tunes loud, It’s no where near face melting volumes I’m talking about. I’ll put a meter to it tomorrow and give some numbers, but I’d be surprised if I was much past 85 dbs.


@erik_squires ,

I have been moving some 2’x4’ foam, absorbing panels around as well as some pillows and even a couple of blankets. It’s hard to explain, but the room probably doesn’t have 60% walls and it was worse. Not one wall is solid all the way from side to side. The front wall is the closest with only a doorway (no door)


I just googled the Hegel & those Kef speakers and wow.  If you can go by MSRP, that should be some pretty good stuff.


I hope you understood what I was trying to say.  I probably should stop posting after bedtime.🙁


So this morning after everyone left, I put on several different CD’s and cranked the volume.  I played some jazz and some rock and maybe it’s because it was morning (?) nothing distorted!  I pulled out the sound meter and I got well into the 90’s and the light flashed when I went over 100.

I’m going to try this a couple more times. Listen at night and listen again in the morning.

Maybe there’s nothing wrong with my equipment or my room. Wow, maybe it’s my ears? 


It's called "distortion," and you should turn it down until it doesn't hurt behind your ears--you know. That's how loud you can play it for now.

Next step is make an upgrade to lower the noise. Begin with cables.

Enjoy. It's fun!

@curiousjim  I think that is a serious possibility.

Some nights, nothing I listen to sounds what I would describe as great, and I attribute it to my mood fluctuations or maybe how tired I am.

Also, noting that you typed that the time of day affects what you hear, maybe it is the power coming into your house?  Although I would actually think the power should be "cleaner" in the evening.  Are you running any dedicated lines for your system?



I have pretty good power here, when it works. We’ve had seven transformers blow in the last fifteen months! I am a Audience AR6 power conditioner. 

Thanks for your thoughts.


A perspective from a non-technical music lover:

I have a two watt tube amp matched with 92 efficient speakers. My room is about 210 sq ft. The sound was flat, and compressed (in terms of sound stage).  In addition, the bass was thin, and frequency response was distorted in the midrange.  I assumed I needed more watts or more efficient speakers.  Hence, I tried speakers that were 98 efficient.  Nevertheless, the subsequent results did not improve. The new speakers played louder but with the same issues.

Through further exploration of my room, I found the ideal speaker placement for my room and then added some diffusion and absorption treatments.  

In short, my 2 watt amp and 92 efficient speakers now perform as originally desired relative to my preferences - warm with natural timbre, sufficient detail,  and excellent sound staging and dynamics.

Know Thy Room and Thy Self


“Know Thy Room and Thy Self“

I like that and I have been working on it!



There are quite a few factors in each system, starting with maybe power to the home, room resonance problems, equipment not meant to play well with certain other equipment, and yes even yourself. 

 In my system/room setup, I can hear the system distort just before the room is saturated. This happens at way above my normal listening levels. Sometimes my ears say 'no way' before the music does.

 Funny thing though, there are even times when distortion is present and I don't mind, but that is an exception for sure. 

 To make a guess in your system, I'm thinking speakers and room placement. Maybe even some first reflection treatment. But yah, speakers. 

“I am a Audience AR6 power conditioner“

Should read, I have an  Audience, AR6, power conditioner.


I’m still not sure it’s not my ears.



I wish everything was recorded at the same level!

I am really sad to say it is my ears! Some of the music I listen to in the morning sounds good and sounds sharper in the evening. Same everything, Equipment, tunes and volume. If I keep it simple, like Bill Evans Trio or Art Pepper it is as bad, but the more instruments the worse it gets.


You've probably arrived at that certain age when you must pay the price for your extravagant volume habit. Surprised you hear anything but tinnitus.

Look at the Stereophile review of the Kef Reference 5 (2017). Go to measurements and look at first graph, the impedance curve is the solid line. 1k - 5k they appear easy to drive. I would try reducing the 4' distance from speaker to side wall, if there are walls, to 3' for starters. How far to the back wall ?  Hope this helps, Best.

In my opinion there is nothing wrong with your gear or your ears. The fundamentals of the alto sax and electric guitars do not go much above 1K hz. The piano obviously does but in most songs the range usually does not go much above 2.5K hz. So the harshness you are hearing is probably in the harmonics, which are being reproduced by the tweeter in your KEF's which also happens to be the frequency range the ear is most sensitive to. (3K-4K). 

Tone control is one way of dealing with the issue or if you are averse to that, room treatments would be the way to go or possibly a combination of the two.

As far as the music sounding better in the morning, it could be because there is usually more ambient noise during the day, which could help mask some of the higher harmonics. Is it possible that you are listening more critically in the evening and using the music as more of a background during the day?


I just reread your reply and here goes. No I haven’t noticed any warning lights. No blown fuse and my speaker wires are 8’ long.