The cloud?

It seems that unless you need to access music remotely due to travel, a cheap hard drive is the way to go. They can be small and many also have Bluetooth if that is useful for you.

PLex media server runs on your computer and enables hi res
remote internet access ( not just for audio but HD video
and photos) via web browser or mobile apps.

No need for files to leave your home or be copied to the
cloud which will take forever for a large library initially
as pointed out.

PLEX server is free as is browser access and just requires
setting up an account on plex.tv site. Mobile apps are $5.

Plex has its quircks still but overall works and sounds
great.

I run plex on an amazon TV box at home which supports high
res audio formats and has toslink audio out to your dac of
choice. Your hdtv becomes your user interface.

I also listen remotely using computer browser from work and
from various mobile phones and tablets.

This past weekend I was listening to my home music library
remotely while out of town in DC on an overnite vacation
using good quality headphones with my wife's iphone.
Nice!!!!

You can do this with Microsoft OneDrive. Not sure how the client is presented on a MAC but on Windows 8 and Windows 2012 Server the OneDrive client service maps a drive on your local machine to the cloud repository. It is like having a regular local drive. Of course there will be some latency issues with this and it will not be 100% reliable as a physical local drive. This will depend on external factors such as the reliability of your home internet and the reliability of Microsoft Azure Cloud. The company I work for is moving tons of apps and servers to Azure and we have had good success with Azure.

You have given me an idea of trying this myself with my JRiver WIndows 2012 Server system and Benchmark DAC2.

This whole Cloud thing is such a marketing joke!

Are you kidding? I use iCloud to backup my iPhone. It works great restoring a corrupted phone and initializing a new phone when I upgrade.