Is It Okay To Disconnect NAP 250 Without Switching Off HCDR

It's fine to disconnect from the Hicap, so long as the 250 or 200 is switched off. I'm not sure what you mean about disconnecting from the 282, which there is no need to do, as the amp connects only to the Hicap. 

Thanks for the quick response. What I mean is after I switch off the NAP 250, I will disconnect the cables at the end of the NAC 282 with the unit still powered up by the HCDR. I want to replace the NAP 250 DR with the NAP 200, and then put it back in again.

Are you connecting the 250 directly to the 282? Hopefully not. Just unplug the power amp from the Hicap. 

I presume cables can be plugged and unplugged from the HCDR with switching the unit off.

So long as they don't carry power. 

Murphy's Law is telling not to disconnect anything under load, so you should turn the Hicap off (and everything else you want to disconnect) and wait at least one minute after the Naim logo light faded out before touching anything.

Important: Let the units drain out while they are still connected to the main. Don't ever pull out a power cord until that critical minute is gone.

That warning said, nothing bad should happen if you disconnect a turned off power amp from the Hicap, and if you plug in another one that is turned off as well... Unless you unplug the Hicap's power cord by accident while pulling out other cables around it (GO, Murphy, GO!).

Bye.

I would advise that you switch off all the components in your system. Do remember that the cables carry continued earthing and signals...

I'm with Stoik here.  Although at Naim we would never bother to switch anything off  when swapping cabling (Naim speaker plugs made quick removal and replacement easy), this was mainly for speed during demos.  And we weren't infallible either - every now and then you'd forget to remove the speaker cables and the shriek from the speakers would reprimand you in no uncertain terms. And sometimes you'd end up blowing the tweeters.  Not so bad when the service dept is in the same building.  Rather more annoying if it happened elsewhere.

At home, I switch things off when removing or connecting cables.

Richard Dane posted:

At home, I switch things off when removing or connecting cables.

Me too. Why on earth take the risk over a few minutes time?

I have noticed recently that dealers rely on the mute button to switch the speaker cables between speakers with the system under power. Apparently they find this a low risk venture and/or have yet to get stung?

When comparing amps, shouldn't it be possible and safe to connect both amps to the HCDR in parallel? 

No one but you will be responsible or liable for the consequences of damage arising from an unforeseen accident. So do as you see fit. Personally I would power down to avoid the possibility (even if small) of several days/weeks silence in the lounge. Blowing my A60 because two filaments of my QED 79 cable touched across channels taught me this the hard way. I learned and changed behaviour and removed power before removing anything else. If it hadn’t happened I might today be none the wiser or all the poorer. Who knows which?

Possible, yes.  Recommended, no.

Thanks for all suggestions to do it the safe way. The reason I am hesitant to switch off the Hicap DR which in turn will power down the NAC 282 is the concern that the system will need some time to come "on song" with the brief power cut-off of both HCDR and NAC 282. I have read that the preamps need two to three days to stabilise (sound good) unlike power amps which will need about an hour of warm-up.

I have done this test, running a NAP 200 and 250 DR off a Hicap DR at the same time, and a bit pointless, as it may create an earth loop?

Also it was a bit risky, reading the comments above, and it Richard Dane says not recommended, then I won't be doing it again. 

Is there any purpose at all for the multiple output sockets in a Hicap? Or are they there only for historical reasons? I couldn't find any setup in the connections guide which uses more than one output.

If you run 135s or a 300 you need two sockets. If you passively biamp or triamp you need two or three respectively. 

ryder. posted:

Thanks for all suggestions to do it the safe way. The reason I am hesitant to switch off the Hicap DR which in turn will power down the NAC 282 is the concern that the system will need some time to come "on song" with the brief power cut-off of both HCDR and NAC 282. I have read that the preamps need two to three days to stabilise (sound good) unlike power amps which will need about an hour of warm-up.

The system will still be warm so I wouldn't get too hung up on the brief power down. It sounds as if you're trying to do a direct A/B comparison between the two components, likely based on a specific track or two. This immediate approach tends to focus on the apparent hifi differences. I've found it's better to listen to gear more in the long term with a variety of music. Get relaxed and see where the musicality leads you after a couple of days. Then switch back and do the same. A hasty approach could lead to a hasty decision, or damaged gear.

+1 to the above.

Quick A-B comparisons at this level can be tempting, but may lead to a trap. In my experiences the best tests are along the lines: component A - 1 week, component B - 1 week, component A - another week....

Thanks for the advice. Certainly makes a lot of sense. Though I am not trying to do a quick A/B comparison by switching between components with short listening sessions. I am just concerned that by briefly switching off the components, even for 5 to 10 minutes, it may affect the performance of the equipment particularly the HCDR and preamp that it is powering.

It appears that the brief power shut-down will not affect the performance of the system. Next time I'll switch off all equipment. The exercise will likely take less than 15 minutes.