Thanks. I have read the entire thread. My question was simply whether to go for an external drive on internal one. That’s all. NAS is excluded.
As long as there is no difference in performance between the two, I am leaning towards an external USB 3.0 drive, simply because of the versatility of swapping out storage down the road.
Does it make sense?
You’ll be fine using a USB3 drive – for storing and playing music files you will not notice any difference in performance.
I’ve been using two of them (LaCie Rugged) connected to a NUC6 for over a year for the same reasons (one for music files, the other is synced every night). In fact, I take the backup disk with me on holidays – here’s Roon-on-the-go playing to the Meridian F80 on the mantelpiece:
Did I hear “Roon on the go.”. 
I went with internal, purely because I’ve had more external drives fail in the past, and I liked the idea of the self-contained unit. However, I keep two external drives with a copy of my audio, one is ExFat so could take over storage duties quickly should the internal drive fail. You can’t really go wrong whichever way you go, just ensure it’s backed up!
What you see is what you get, I’m afraid: MacBook running Roon, harddrive filled with music, good old cable to F80.
Since the last mile of the Internet connection here is covered by smoke signalling, probably for the better. 
I ended up buying this from Best Buy yesterday.
Transferred all my music files to it, directly connected to computer (man, that USB 3 is fast!), then attached to the NUC. Then pointed my remote on iPad Pro to the drive, and was up and running in no time. So far it has been working great! Thanks everybody for your help!
Correct! this works perfect for me. I m not yet on ROCK but Roon on my MacAir with Ext HDD USB connected, although little caution in plugging it in and Eject process, but once ROCK is up and running on NUC then less worries. This setup is very handy and very easy for me too!
Any thoughts on which type of drive in a NAS will sound better? I know, opening a can of worms here but has anyone compared different types of drives in their NAS?
Also, wouldn’t 4 SSD’s in the NAS be more reliable than HDD’s?
SSD would always be better if cost is not a concern - I think!. Which NAS? wow! i think yes you are right, can of expert users on this forum 
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Wouldn’t a spinning internal HD introduce vibration into the NUC and therefore affecting SQ? I’d have thought an internal SSD is more “audiophile”.
No offence to anyone, but perhaps we are now entering into the realms of “how many Angels can dance on the head of a pin”
The words “No offence but…” always precedes an insult even if unintended! 
To try and answer the question sympathetically, if the vibration of a HDD can cause mis-reads or jitter then you probably have bigger problems like an imminent disk failure. A drive working normally might produce some vibration noise and be audible at short distances but it shouldn’t affect data.
Apologies for any unintended offence I may have caused to anyone with my earlier post 
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To respond to @Tategoi point on the basis of my own experience of HDD vs SSD. I have a Wyred4Sound Music Server which was originally fitted with HDDs which I subsequently had replaced with SSD. In terms of pure SQ, I couldn’t honestly tell the difference, but then again I have reached an age where my hearing is not at its best - I certainly do not have “golden ears” 
. Others may have different experiences. The benefits that I did notice with the SSD was that it was faster to boot and, as is to be expected, quieter (probably also more energy efficient and more reliable), but to me did NOT make any difference to SQ. When fitted with HDDs, the Music Server was far enough away from my listening position for any “mechanical” noise, as slight as it was, to be totally irrelevant. I suppose that, knowing what I know now, I would not have gone to the expense of replacing the HDD with SSD.
Regarding the point on induced vibration into a NUC affecting SQ. I have just, only yesterday in fact, built my NUC ROCK system (NUC6i5SYH, Samsung SSD 850 EVO, HyperX 8Gb Ram and a 2TB Seagate Barracuda HDD internal drive for my music library). It is sitting right next to me, in the study as I type, and playing music in the Lounge downstairs. It is totally silent in operation and, if I put my hand out and touch it, I can feel the slightest vibration (hardly any in fact), whether that is having any effect at all on SQ, I cannot say, but from my past experience with the Wyred4Sound Server, I would say, to my ears, none!
Audiophiles spent hundreds on footers and thousands on racks with the objective of isolating the equipment and reducing effect of vibration to the minimum. Going by this I would like to think that vibration from a spinning hard disk would have an adverse effect on the SQ.
@Tategoi, With respect to these Audiophiles, who are entitled to spend what ever they like in seeking “audio Nirvana”, it was, as I stressed, my own experience that HDD vs SSD brought no improvement to SQ to my system. There are other sources of vibration which could cause an impact on SQ (mounting Loudspeakers on a sprung wooden floor, for eg) which might benefit from some form of anti-vibration remedy. Your original post sighted, specifically HD induced vibration into a NUC and, as I stated, it is my own experience, in my system and with my level of hearing that I could hear no discernible difference in SQ. Others might, and might wish to spend money on some form of “anti-vibration” mounting, I personally wouldn’t see the need.
The vibration on a turntable and its effects can be demonstrated. In the extreme, you could make the stylus jump whilst dancing but digital files on a hard drive are another thing entirely.
Absolutely agree. I would certainly spend effort, and money (and have), on ensuring that my Turntable is stable, but as the ground floor in our house is on a solid concrete plinth, vibration is not too much of an issue - at my age there is not so much dancing, but take the point .
The simplest and free solution to the scare of vibrations from a 2.5" hd is to place the NUC somewhere else than on the hifi rack.
It is small enough to be screwed to the wall, on the floor or in another room. It is only imagination that prevent it from not being on the hifi rack for those that is afraid of vibrations.
Before I go looking and make a choice: I need a 12TB external hard drive, any suggestions based on what’s available currently?
Thanks
