[Kw6]

Funny how I am now thinking of power conditioning for my Cayin A 300b Mk II integrated amp. I am having a speaker thump on my left speaker when I turn of my amp. My dealer told me to try it with a line/surge protector. The only one I had from yrs ago was the Monster Cable HDP 1250G+. So I plug my amp into the plug for receivers. I wasn't too happy thinking adding this old power conditioning unit will squash my dynamics and maybe cause some hardness/brightness due to the cheap components inside. But to my surprise the sound now has a bit more clarity and analog ease.

What gives? Now I am looking into a Panamax MR 5100 which has delay to shut off amps to maybe help with the thump. What do you guys think of Panamax. On a side note what causes the dreaded thump when turning off amp. Thanks!

[Speedskater]

I doubt that the AC power line has anything to do with your problem.
How old is the Cayin?
Does it thump with no interconnects plugged into the Cayin?

[Kw6]

You are right not power line related it was the 300b tube I will confirm tomorrow. BTW is the Panamax better than my old Monster Cable HDP 1250G+?  I wonder what's in the filtering to give the presentation more ease and details?

[Kw6]

I was mistaken it might not be the tube it could be in the circuitlike a bad capacitors in power supply or resistor.

[G.Michael]

BTW is the Panamax better than my old Monster Cable HDP 1250G+?

I use a Panamax M5300EX in one of my systems.  I bought it thinking it would be a nice budget power conditioner, and it has exceeded my expectations.  Well built, with common-mode filtering along with usual (differential mode?) filtering.  Good layout and lots of outlets.  When I took off the cover (out of curiousity) I was impressed that these cost as little as they do.  As for the sonic enhancements, I'm not sure, as I've long used fairly good power conditioners, most all of which have been DIY. 

I'm not familiar with the Monster conditioner, but one spec that makes me think it and the Panamax 5100 are not comparable:  Weight of the Monster: 3 lbs.  Weight of the Panamax: 12 lbs. 

[FullRangeMan]

Some power conditioners dont use transformers and have low weight.

[DeSelbyofDalkey]

+1 regarding the thump. It is an amplifier issue, not power source issue. I have an Acoustat TNT-200 which makes a small thump when first turned on by my Luxman 5M20 does not because the Luxman uses relays to keep the signal off until the amp is ready whereas the Acoustat does not use relays. If the startup thump is new, then it should be attended to.

Insofar as power conditioners are concerned, I have used a Panamax MR4300 for several years very happily. It is similar to the MR5100 in many ways with the obvious difference being number of outlets. That said, it is unlikely that a power conditioner will remove the startup noise from the amp.