Loss of bass & full spectrum sound

@ fishing716,I believe I would start with your power at hand!,high -end recepticals for each componet,a dedicated 10 gauge electrical line for each componet,with a dedicated ground for each componet with a 20 amp breaker for each componet, this is what I use,problems?,I have none!,the sound will improve dramatically as well!,this will take a few hundred dollars to do,the pay-off sounds in the thousands!Happy listening!

I'm sorry but don't understand all these details such as 10 gauge electrical line(what is that?)
Also 20 amp breaker(what is that?)
I apologise if I'm not knowledgable of electrical terms as you assume.
I'm just a music listener

John @ audioconnection
That is a very helpful suggestion
I will contact an Electrican
This is Anthony from Staten Island
I've been in your shop many times and purchased B&W 804n from you 15 years ago.
Say hello to Mary your receptionist

Hi @fishing716 
I'm just wondering if you ever solved this problem. 9 years later I hope so! Anyway, I was searching the internet for any insights on this. I seem to be experiencing exactly the loss of bass that you've described. The Bass sounds hollow and thin. But the first few days of owning the amp, I was blown away by the clarity of sound. Music had amazing bass & clarity even at low volumes. Now I get nothing like it. The amp will still play loud, and I do get bass frequencies, but everything sounds very average now.  Anyway, if you found a solution, I'd love to hear it. I'm going to call my supplier tomorrow and explain the problem. I've never experienced an amp sounding so good one day, then just so so the next.

I've now rung Yamaha and some service centres. They are inclinded to think that the problem we are both descibing is more so the speakers/drivers are the issue.... not the amp. I really hope my speakers are ok... and an amp replacement will fix the issue... but it sounds unlikely. The amp I just bought is the Yamaha RN803D by the way...

I have experienced the same with my Pass Labs 250. It is not speakers as I have several. I just wonder if it's the density or the air in the room at the time. Mine has no pattern to it. I get blow you out the room bass most of the time, but then all overtime the amp is just thin sounding in the bass. Come to think of it, this has happened with several of my amps. I have no answer.