If you can't find a humbuster 3, here is a cheap alternative.
http://shop.emotiva.com/collections/accessories/products/cmx2
@wijnand
I tried a Shunyata Triton and it had no effect on the DC hum in my 2300. I was told by Classe’ that the source of such a hum is nearly impossible to track down and that a filter is the only real solution. The advantage of the internal filter they provide is that it eliminates all that extra hardwarenand extra power cords required by an external filter. (Have you considered consulting with the Netherlands Classe’ dealer to see if they could install the internal filter? The folks at Classe’ in Canada told me the retro-fit only takes about 15 minutes to do) Only your ears can determine whether an external filter will affect the amp’s sound. I suspect it might.
I now use a whole house surge protector and run my amp via a Shunyata Anaconda Zitron power cord directly into the wall. I use Shunyata’s $200 Defender at the receptacle. I found this set up to be better than any conditioner when it comes to high current amplifiers. Of course, your mileage may vary.
Vance
@vhiner1
Yes I think I’m going to ask my dealer if they can take care of it. The thing is that I have to mis the amp for maybe a few weeks, but they probably have something for replacement in the mean time.
For me music is a bit restles when connecting the amp directly into the wall.
Thanks for the advices i’m going to do my advantages with it.
Good luck!
I hope you can solve this annoying problem.
Problems solved!
I did a service request about the fan noise of the P5. It seemed the sound of the noise was not very unusual. I personal think there was something wrong with one of the fans, which made the sound a bit louder than acceptable.
From the support I got the recommendation to make a trade up deal and trade up the P5 for a P10 and so I did. The P10 has a passive cooling on both sides of the unit and that solved the fan noise!
Another problem I had was hum from my poweramp transformer. I was made aware in this tread there is a problem with hum of the CA-2300 and that there is a fix for it. When I connected the poweramp to the P5 there was an annoying hum in the room. When the poweramp was connected to my old powerfilter I thought it was free of hum, but the hum seemed only less loud.
I went to my dealer to make an appointment to get the fix for the CA-2300, before I received and tried to fed it by the P10.
Last weekend I received the P10 and fed the poweramp by the P10 in the hope it was silent and it is!! It is silent like it isn’t even powered on. So I think these two are ment for each other and they stay side by side for a long time! Humbuster P10 
Thanks to all!
@wijnand - that is a happy ending involving an upgrade - well done!
@wijnand thanks for sharing, so finally I should upgrade to P10 too, but i’m afraid of cost… Was the trade-in handled by your dealer or via PS Audio? Besides the fan noise and transformer hum have you noticed any improvement in SQ 
?
I’m trying to justify this upgrade for myself… :))
THX
@maniac the P10 was a significant improvement over the P5 in my system. Aside from the fan noise on the P5 it didn’t open up the dynamics as much as the P10.
On another note, how do you find the EC 4.8 in your system? Is it noticeably better than the PWD direct into the power amp?
maniac said: but i'm afraid of cost
@wijnand
Congrats!
@maniac
Yes indeed the cost… is the only minus, but that is the only one or maybe the weight and the size of it.
I opened a ticked so PS audio made the way is this case.
The P10 is an improvement over the P5, but it’s all relative. The most important things for me are the lack of fans and the silence of my poweramp being free of hum.
I guess you would be very happy whit the upgrade. :-bd
But on the other hand good is good!!
Good news!
@stereophilus are you feeding your amp(s) also from P10 ? I have noticed that when I used Supra md06-eu/sp between P5 and amps i got limited dynamics and also sound was less detailed. I had that setup due to lack of receptacles from P5, but then plugged both amps directly to P5 together with preamp and PWD and it’s better now. I had to omit P5’s filtration for TT and headphone amp (yes I know P10 with it’s 9 receptacles is starting to smile at me to buy it )
In regards to EC4.8 - in 1st place it’s night and day to preamp which was inside my former integrated amp ECI5mk2. That was the reason why on the integrated I was going via HT input directly to the amp - more dynamics, more air, more details, faster bass. But it was only single-ended connection as there was no balanced input for HT on the integrated ECI5mk2.
Now to my current setup - there is only very very small difference between PWD direct to AW400 NADA blocks and PWD-EC4.8-AW400 . Still there is a little bit more air when going direct. But going via preamp gives me better convenience switching to other analog inputs (TT, TV, DVD player) and also I don’t have pops when switching sample rate with 2.4.0 firmware Now I’m waiting for ordered HiFi Tuning fuses for the NADAs and fresh bottle of Kontak contact cleaner as the old one I had evaporated (even in properly closed original bottle… ). There is going to be audio show in October here and I know local PSA dealer will be present there so i’ll probably try to arrange meeting to discuss trade in of my P5 to P10
maniac said: fresh bottle of Kontak contact cleaner as the old one I had evaporated (even in properly closed original bottle.. )
@maniac yes, arc ref 150 directly fed from the P10. The ref 150 does not like any filtration in the power line, but enjoys its power from the P10 very much. Thanks for the info on the EC4.8… It seems from your report that PWD direct to power amp is at least as good as this preamp.
@stereophilus yes, correct, PWD direct to amp or via EC4.8 is nearly the same
Soon I should have upgraded one pair of XLR interconnects from preamp to amp so I guess this will help EC4.8 to perform even better than now
wijnand said Problems solved!I did a service request about the fan noise of the P5. It seemed the sound of the noise was not very unusual. I personal think there was something wrong with one of the fans, which made the sound a bit louder than acceptable.
From the support I got the recommendation to make a trade up deal and trade up the P5 for a P10 and so I did. The P10 has a passive cooling on both sides of the unit and that solved the fan noise!
Another problem I had was hum from my poweramp transformer. I was made aware in this tread there is a problem with hum of the CA-2300 and that there is a fix for it. When I connected the poweramp to the P5 there was an annoying hum in the room. When the poweramp was connected to my old powerfilter I thought it was free of hum, but the hum seemed only less loud.
I went to my dealer to make an appointment to get the fix for the CA-2300, before I received and tried to fed it by the P10.
Last weekend I received the P10 and fed the poweramp by the P10 in the hope it was silent and it is!! It is silent like it isn’t even powered on. So I think these two are ment for each other and they stay side by side for a long time! Humbuster P10Thanks to all!
I know my reply is very late because this thread is already old. I also have a Classe CA 2300. Its a tremendous amp in my view but there is HUM in this power-amp from the very beginning due to an unsymmetry (which means DC in the current) in the power that is being delivered from the wall. I tried to fix this HUM with a PS-Audio P3 and it worked - but the CA2300 lost its soundstage in a way that I wouldn’t decide for this device. My question - how is it with the P10. Could you recognize any degradation on the sound stage or did it work perfect in your opinion.
BTW I tried also a HMS RC 1/1 and this leads also to an end of the HUM in CA2300 but unforunatly also to a slightly degradation on the soundstage
Would be nice if you could give me your impression
Thx and best regards
Joachim