FWIW, The ASIO spec itself only allows a single audio interface.
With multiple units (from different companies), you'd have potential clocking issues (tracks drifting out of sync), etc.
Not an elegant solution to a more complex setup...
My thoughts on MOTU:
Yes... MOTU does make some "consumer" level gear.
IMO, Their consumer level gear is better than many other companies' offerings.
ie: The Ultralite AVB offers great bang-for-the-buck ($650).
- Average noise-floor is ~-114dB
- Round-trip latency performance is excellent (sub 5ms at a 64-sample ASIO buffer size 44.1k)
- Routing is extremely flexible
Their larger (full rack) AVB series is what I'd call "professional" level.
Specs are actually slightly better than the RME Fireface UFX.
- Average noise-floor is ~-117dB
- Round-trip latency is sub 3ms when connected via Thunderbolt
- MOTU has full "PCIe via Thunderbolt" support (actually available for a good while now)
Now, are the MOTU AVB series on par (fidelity wise) with boutique converters like Burl? No.
You can't expect that... given the cost.
You could absolutely track a professional sounding record with the MOTU 1248.
Regarding USB vs. Thunderbolt:
Under ideal circumstances, Thunderbolt offers performance equal to PCIe.
The best USB-2 audio interfaces (like RME's Fireface UFX) offer low-latency performance that's very close to the best Thunderbolt units. In fact, comparing the Fireface UFX to the Apollo, at the same ASIO buffer size, the Fireface UFX offers slightly lower round-trip latency.
At a 64-sample ASIO buffer size 44.1k- Fireface UFX yields 5.1ms total round-trip latency
- Apollo yields 5.4ms total round-trip latency
The smallest ASIO buffer size offered by the Fireface UFX is 48-samples.
Total round-trip latency (at 44.1k) is 4.3ms.
The smallest ASIO buffer size offered by the Apollo is 32-samples.
Total round-trip latency (at 44.1k) is 3.9ms.
Even for someone who's extremely picky about latency, that difference is minute.
(You can run heavier loads at a 48-sample ASIO buffer size than at a 32-sample ASIO buffer size.)
FWIW, Sonar isn't adding bottom-end to recorded tracks.
If that's happening, it's something on the front-end (mics, preamps, A/D).
If you have the budget for boutique gear, it'll certainly deliver.
But... I think one can become "choice paralyzed" chasing perfection.
"Perfection" can also be a moving target.
No different than talking about the perfect instrument (guitar, bass, drums, keyboards, etc).
Our idea of what's "best" can change (especially over time).
At some point, fidelity is good enough.
Song and performance will handily trump all the above.
I don't think any record has ever been bought (or not) based on the converters used... or the sample-rate.
If the Goliath offers low-latency performance on par with the RME Fireface UFX (when connected via USB), I seriously doubt you'd be disappointed.
