"What is Thunderbolt?"
In short, Thunderbolt is a new technology designed to support high resolution displays and high performance data devices. It utilizes the MiniDisplay port, which replaces FireWire 400 and 800 ports on Apple's latest Macs. Basically, Firewire and Thunderbolt are electrical standards that traditionally utilize differently shaped ports. That said, a Thunderbolt port can accommodate the Firewire standard with a simple $29* adaptor.
Therefore, in the context of Focusrite Saffire interfaces the most important thing to know is that they are 100% compatible with any Thunderbolt port. With the adapter, just think of it as Firewire is running 'through' Thunderbolt. Simple as that.
*Average price from Apple.com and other major electronics retailers
"So I need to buy a $29 adaptor... Why don't I just buy a native Thunderbolt interface?"
Simply put, audio interfaces advertised as Thunderbolt are extremely expensive – much more expensive than any Saffire Firewire interface + a $29 adaptor! This aside, the benefits of Firewire are still clear: high channel counts and excellent bandwidth. Having your Firewire audio interface on its own dedicated bus means that available bandwidth isn't divided among other devices plugged into your computer. Also, you will be able to keep your USB ports free for the myriad of other devices you might want to connect, such as MIDI controllers, iLok keys, hard-drives, and even mobile phones.
"So will Firewire meet my needs? Tell me more about the Saffire Range..."
Yes! Firewire is excellently suited for audio recording and more than capable of handling large channel counts. With a Saffire you can still record with zero latency by monitoring at the input stage with Saffire Mix Control. Audio professionals world-wide still choose Firewire because it provides ample bandwidth and simply gets the job done. Focusrite Saffire interfaces sound fantastic no matter what port you use – and sound is everything, right?
Focusrite fully supports using Saffire Firewire interfaces with the Thunderbolt port on your computer.
Remember that it's simple: Firewire runs 'through' Thunderbolt.