Hey edsky…
Yes the sr blue will need long burn in time…mine sure did and at times
sounded not so good…(thats part of the settlling in burn in phenom)
after a couple of weeks sq started taking shape…and yes bass will
tighten up and become better defined…
Hang in there friend
Had a “lightly used” SR Blue kicking around I’d forgotten about, bought it for a piece of kit I’ve since sold on and put the fuse in a drawer unused.
Happy to discover yesterday that the Current rating was compatible with my BHK Pre, so put it in.
No idea about hours on it from new, the kit it was fitted to was barely used, so less than 100 hours I’d have thought.
Immediately better sounding, like it a lot. Big improvement.
See how it sounds with more time on it.
Following this thread as I may get an Orange down the line for the BHK and my Directstream dac down the line.
Does the BHK250 have to be on for the rail fuses to get burned in? Or is it sufficient to have it in standby mode?
Standby mode is fine. In standby the rail fuses are active.
I would like to suggest to keep a note the direction of the SR Blue you put in. You may have just happened to have it in the right direction since you liked the improvement. However, I would suggest to have a try to reverse the direction to see if you like it better or worse. Next time if you want to try an Orange one in your BHK Pre, try the same direct first, more likely than not, you will have the right direction, that was my experience when I upgraded all my Blue to Orange.
SR fuses are very directional. Please see my comment to Gazjam above. In my experience, either direction will give you some improvement in frequency extension, however, when you have the right direction, to me the most obvious sign is more detail, resolution, the less obvious are more 3D, more natural decay, etc. i.e., more SR “house sound”. SR rep told me the following tip to find the right direction, put it in, listen for at least 1hr, reverse the direction, listen for at least 1hr, then burn-in at your preferred direction for at least 25 hr, preferably about 100 hr, have a critical listen, then reverse the direction just to make sure you made the good choice of the direction. Another note, SR stuff usually require quite a bit burn-in time. The most frustrating thing was the SR stuff’s burn-in process was not linear regarding improvement, especially within the first 25-50 hrs, sometime, the SQ was obviously worse, sure testing my patience.
Hi zheng4…
An easier way than changing the fuse direction…get one of these…
a voltage detector pen…hot side of fuse will either light up the pen
and or sound a tone on the fuse hot side…then place the fuse according to directionality… here is a link
This could save some effort…on my Emotiva XSP1 Gen 2 there are
2 covers to remove to get to fuses a third is easy access…
So the pen is a great helper here…
Hope this helps a bit
Just flipped the fuse in my BHK
This is they way.
Had it in the “logical” direction, SR text running from the rear of the amp inwards, following the direction of the text.
Way better than the stock fuse, but the soundstage felt focussed (compressed?) towards the centre?
A bit light in the bass too, had put that down to it needing time on it.
Flipped the direction this afternoon, left the amp running for an hour and sat down to listen.
“No brainer” better.
So the SR text on the fuse running “out” the amp worked for me, though who’s to say it just wasn’t that the label was put on backwards in the factory! 
I’d say just try it in either direction, can say that you’ll know the right way…right away.
My experience seems to echo a lot of others, the difference isn’t subtle.
Keeping an eye on the Orange vs Blue discussion…
DS Dac is still on stock fuse.
So it what direction should the hot side face?
Hey audiodlephi …On the blue fuse afaik the reading left to right sr side of fuse faces hot side of fuse block and on the orange the side with s reading left to right the s side faces hot side of fuse block…
Hope this helps
The orange fuses on my preamp were sounding very very good
with just 2 hours of runtime…I’m letting them run in more again until
early evening to give them a work out…plan to take a listen again then.
I did read Paul’s very helpful reply about just leaving the unit on is
good enough…I had read a similar explanation elsewhere …
Hi David,
Will the light up pen also check the hot side of the fuse block?
Audiodelphi
Yes, on the hot side of fuse block some will both light and or play a tone
on the neutral or opposite side no tone or light…that is how to know …there are many models…on amazon check 'em out
I think Paul mentioned rail fuses only, not sure about small fueses.
Hey zheng4 …
You are most likely correct…thanks
A naive question since I don’t know anything about electricity. Can you test a fuse when it’s not in use? All the fuses of PS Audio gears, except the DAC Sr, are accessed from the fuse holder in the back.
Thanks Paul. Is there any fuse on the Preamp, DAC, or BHK amps that requires a full power on?
No question naive my friend…an out of the fuse block fuse can be tested for conductivity with an ohm meter…but not directionality…afaik sadly…
But to test for hot side of fuse holder fuse must be in fuse holder
and unit powered up…
Yours is a great question not naive at all…
I am thinking just off the top of my head and only a conjecture
but perhaps with volt detector pen it could be possible to get an
indication light or tone with fuse in place and unit powered up by
simply bringing the pen in proximity to the outside of the fuse holder.
In my power amp Parasound A21 …I didn’t know either…but reading
on an a tweeks and isolation thread I found an illustration of the same
type of fuse holder my A21 uses worked for me and could perhaps be the same configuration on BHK gear… I don’t know which way PS A BHK is configured at fuse holder…
Here is a link from audioaficionado to help illustrate:
https://www.audioaficionado.org/showthread.php?t=12259
Hope this helps you further…happy trails friend
Hi Paul, How do you route your incoming AC through the fuse holders in your PS Audio gears (BHK pre, BHK 300, DACSr), from internal to the fuse holder cap, or other way around? Thanks.
Great question zheng