storage options for MacBook Air

When I had my MAC Book Pro, I stored all my music on an external  LaCie hard drive (used Thunderbolt cable) and not on the MAC Book Pro computer.   I never tested this but my retailer said playing music from an external hard drive would sound better then if the music was stored on the MAC Book Pro computer.  My LaCie hard drive was backed up to a 2nd hard drive.

I have since replaced my MAC Book Pro Computer with the Aurender N10 Music Server.   My audio system sounds more open, more natural, clearer, better bass and I am very happy I purchased the Aurender.  The ability to switch back and forth between Tidal music streaming and my stored albums on the Aurender is now a very easy process (one mouse click).  The Aurender iPAD app is much easier to use than my MAC Book Pro computer.  Album selection is also excellent with several different album selection choices available.  The Aurender N10 Music Sever is highly recommended for its great sound quality and ease of use. 

I also use the AIFF format. And iTunes.

So the answer depends on the number of albums/songs in your library and if you plan to add to it.

I assumed that the external drive was used because you were running out of disk space on the MB Air. Which, as your library grows, is gonna happen.

For example, my Rollings Stones "Let It Bleed" CD to AIFF rip is 455 Megabytes. Not sure how much overhead Mac OS (or OSX) uses on that MB Air. But if an album runs 450 Megabytes per CD you could calculate how much of your library it could hold. 

If you like iTunes (and I do though I use Roon for playback but hear no difference in SQ from iTunes) then maybe consider a MacMini to run iTunes and output to the Ultra Fi. You control the Mini iTunes from the MB Air using Screen Share. That existing external drive could be connected to the Mini. 

hgeifman,
The MB Pro you had probably did not have a SSD drive which I'm guessing is why the retailer recommended the external LaCie hard drive. I've read that it's always good to keep music on an external drive.
I've also read that SSD makes a noticeable improvement over standard hard drive and my MB Air comes with built in SSD which makes my decision difficult.

dbtom2
My library will fit in the MB Air at this point, but you're right 250 GB will run out when my library grows. What Mac are you using?
I control itunes using the remote app and it works very well, no need for two different computers.

I listen to music on a (mostly headless) MacMini. The music is managed by iTunes. I've got almost 3/4 TB on a 2TB WD drive connected via firewire to the Mini.  The Mini USB out to an LH Labs DAC to HiFi.  This is my Roon core. 

I rip and control the MacMini from an iMac which is a Roon remote. The iMac has an Oppo HA-2 DAC/headphone amp for local listening

Both are wired via ethernet and I use Apple's Screen Sharing to manage the Mac, add music files etc.  

Your MB Air is a sweet portable device, an excellent remote control to the hifi stereo but capable of playback to personal listening too. 

Scar972, It can make a difference if your external (mechanical) storage is acoustically noisy.  Other than that your DAC has asynchronous (I believe) input, meaning that timing of the computer and DAC are separated.  What you send to DAC is data - not the music (you can use computer at the same time).  Music is recreated in the DAC by added timing (separate clock for D/A conversion).  I would not transfer files to SSD drive for two reasons.  First is better flexibility of external storage and the second is the fact that it can make your SSD last longer.  Your SSD has limited number of writes for each sector.  In order to extend it drive constantly reshuffles sectors to minimize the use of each sector.  The more free space you have the more years it will serve you.  Don't forget to make backups.  I make two backups to prevent situation when something bad happens during backup destroying both disks.  In addition my second backup, that I keep at work, gives me protection from fire, theft etc.