I think that the only difference is that the BeoLab 4 PC do not have powerlink sockets, hence either will work with a PC. I bought the 'standard' BeoLab 4 for use with my PC, and connected via 3.5mm (line-in socket) using this cable from Steve: 

Location: Warwickshire, UK

My B&O Icons:

BeoCenter-9500.png

Beoremote-Beo4.png

Beovision-10.png

Beotime.png

Beosound.png

Beosound-Explore.png

Beosound-Essence.png

Beoplay-P2.png

Beoplay-M3.png

Beoplay-H4.png

Beoplay-H3.png

Beoplay-Form-2i.png

Beoplay-Earset.png

Beoplay-A2.png

Thanks Guy, that's really helpful.  I don't have the Beoport anymore (I gave it to a friend when I got an Essence), but mine is really a gaming PC, so for gaming audio, they should stay on while I'm playing. I saw a pair in great condition including stands for just over £200 on eBay, which was a bargain, and when I asked him a question about them, he doubled the price!  I'm sure I'll find a cheaper pair though, as I don't really want the stands.  I'll keep my eye out for a pair on eBay, and thanks for the letting me know which cable I need.

I got a pair of Beolab 4 from eBay, in great condition - they look like new.  I got the version which do have Powerlink sockets just in case I want to use them with any of my B&O HiFi equipment in future, but I bought them to use with my PC. As it turned out, I already had a cable with stereo 3.5mm to 2x mono 3.5mm (I don't remember where it came from; I rarely throw a cable out).  I connected them to my PC that way and they work fine.  The volume is very loud, so for normal listening, my PC volume is set to only 4 out of 100! The do go into standby if there is no audio from the PC for about a minute, and that's exactly what I want them to do - in fact the switch on the underside needs to be set to Line In for this, not PC.  If you set the switch to PC they remain powered on all of the time. It's difficult for me to tell if they are on standby or not as I am colourblind and can't tell what colour the LED is, but I have found a problem.  Last night when I stopped using my PC, they did go into standby (while I cannot see the colour of the LED, I did at least see that the colour did change).  I switched off my PC, but when I came back into my office this morning, there was an obvious buzzing/feedback from the speakers.  This is the exact same noise as I get if I unplug the 3.5mm plug from the back of the PC, so must be some kind of earth/cable feedback?  I don't have much understanding of these things though. I'm wondering them if it could just be the quality of the cable.  I think I'll buy Steve's cable that you recommended

Location: Liverpool

My B&O Icons:

BeoCenter-9500.png

Beoremote-Beo4.png

Beovox.png

Beovision-11.png

Beotime.png

Beosound.png

Beosound-Moment.png

Beosound-9000.png

Beosound-5.png

Beosound-4.png

Beoremote-One.png

Beoplay-Portal.png

Beoplay-EX.png

Beoplay-Earset.png

Beoplay-A2.png

Beogram-400x.png

Old enough to have gazed at classic B&O HiFi in Plumbs shop windows in the 80s...

I have had a similar humming/feedback problem with PC speakers - I can't remember 100% but this may well have been with my BL4s.  As far as I remember there were problems when a speaker was either too close to the PC screen (all sorts of high frequency signals inside there!) or too close to a B&O phone PSTN (potential interference from the DECT phone signal).  Does re-positioning your speakers away from other components make any difference? Either way, I would  think that a good quality cable should help resolve.

I've come home from work today and they are not humming, and I asked my partner (who has full colour vision!) to check the LED for me, and they were on standby/red.  I'll keep checking, but I will get Steve's cable, as a better-quality shielded cable is likely to be an improvement on the basic one I have already. Using my PC right now, they are coming out of standby as expected if I do something that causes a sound, and going back into standby about a minute after the sound stops, which is all as I would expect. They are quite close to my PC monitor but that's unavoidable as I am using them as PC speakers.  One of them is also right next to my Beocom 2 phone, but the PSTN (Mk1) that I have that linked to is a good few feet away from the speakers.  

Just a few cents from me. I have a set of Beolab 4 sepakers and have an accespoint placed relativly close to one of them. If the distance between the accespoint and the speaker is to short (<5cm or so) the Speaker is beginning to make ticking noises. So these speakers are prone to some interference from other things. Btw. I am using original MK3 Powerlink cables (the thin ones).

Just in case anyone else has this problem with their BL4s buzzing and not going into standby when connected to a PC via the 3.5mm connection.  The problem kept returning; I would move things around and it would stop, but always come back. I had used a cable (stereo 3.5mm to 2xmono 3.5mm) that I already had.  It was supposedly shielded, but in the end I figured the cable must be the problem, so I bought

Location: Liverpool

My B&O Icons:

BeoCenter-9500.png

Beoremote-Beo4.png

Beovox.png

Beovision-11.png

Beotime.png

Beosound.png

Beosound-Moment.png

Beosound-9000.png

Beosound-5.png

Beosound-4.png

Beoremote-One.png

Beoplay-Portal.png

Beoplay-EX.png

Beoplay-Earset.png

Beoplay-A2.png

Beogram-400x.png

Old enough to have gazed at classic B&O HiFi in Plumbs shop windows in the 80s...