Advice re which hdd for Duo v1

You can mix/match other drives, but they must be either 1.5 TB or 2 TB. (If you replace one of the drives with a 2 TB model, the space will not increase though). 1.5 TB are not a particularly popular size now, so 2 TB might be less expensive (certainly not more).

There is a compatibility list (http://kb.netgear.com/app/answers/detail/a_id/20641), but it is quite dated for the duo v1. I recommend NAS-purposed drives (Western digital "Reds" and Seagate "VN") - I use a WD20EFRX in my duo v1 and it works well even though it is not on the HCL. The other drive is a Seagate (an older model).

I don't recommend "green" drives from either manufacturer. The NAS-purposed drives are just as eco-friendly as the green drives, and are intended for NAS use.

Thanks Stephen for a very informative and helpful reply.
[emoji4][emoji106]I just know that I need to cover my back as both my existing drives are quite well used - although health is good on them according to the Netgear diagnostic tab.
It's my first foray into NAS/streaming audio hence the question. I have backed up as well tho to a portable hd: I have learned that a nas in raid array isn't about back up as such but continuity which I do like. I hate to be listening and it go pop so I'm stuck till PC World opens!![emoji38]