Hey,
Now we're getting some real answers!
According to God and mucka, a fully decked out PT rig is better than a computer running Sonar for the following reasons:
1. PT has farm cards, which for those of you who don't know, are cards which have fancy DSP chips on them dedicated to running effects and softsynths. Instead of having a native system which uses the Pentium (or whatever chip the Mac uses nowadays) doing the work, the farm card does the work for them, allowing the computer to dedicate itself to managing the system instead of doing the heavy number crunching.
The farm cards are sort of open ended; any software manufacturer who wants to write plugs to run on these cards can do so; all they would have to do is get the API or instruction set (or whatever it is you need to write hardware-specific software) from Digidesign, follow their rules, and make software which both PT and the cards can understand.
Because of hardware and complete integration, a full PT rig offers near-zero latency (I'll argue that there is ALWAYS latency, even in hardware synths, but not enough that we can tell...). And the more hardware you add to your system, the more plugs, synths and tracks you can run.
2. The hardware interfaces that Digidesign manufacture sound better than a lot of third-party cards. God feels that this is a critical element in a system which isn't discussed enough; Mucka feels that the 888 interface sounds better than laptop soundcards, and to approach the quality of the Digi cards you have to spend around $1500.
3. It runs well on Macintosh computers.
4. It's more stable than a native system for long recording sessions.
5. You can run 16 instances of Rennaisance Compressor and 5 instances of Rennaisance Reverb (Waves) and an instance of Altiverb (audioease) and have everything playback smoothly.
6. It's easy to use.
Now for Sonar:
1. Much better MIDI implementation.
2. Much cheaper, and you can buy third party Powered Plugins and TC Electronics PowerCore
3. Acid style looping, CAL programming, DXi support.
I think God said it best:
"Honestly, I believe, with enough time, that I could make equally good recordings on HD and CEP or SONAR if I put enough effort into it and have the right outboard gear and mics."
And this seems to be a common thread amongst people who work in any big studio: they take advantage of a lot of the high-end hardware at their disposal in conjunction with Pro Tools.
The high end converters are not exclusive to Digidesign hardware: if you read some of the trade magazines, names like Apogee, MOTU, RME and Swissonic appear all over the place, you can run these with just about any software (including both Pro Tools and Sonar) provided that you have the right card in your computer.
All of the high-end plugins mentioned in these posts will run on both Pro Tools and Sonar. Of course there are some which will run only in PT, and there are some which will not.
A disadvantage that Sonar or any other native software runs against is that it is dependent on the host CPU, which means that it probably won't be able to run 16 compressors, a convolution reverb, and a 'normal' reverb along-side 30+ tracks of audio.
Based on what everyone has said here in the past few posts, I still feel that Pro Tools itself is not needed to make a professional sounding track: it seems that the sound is a result of processing either done with either external hardware (which is software independent), or with plugins which run on all systems. And tape.
The advantage that PT has is that you can run more of them, provided that you have one of their high-end systems.
More two cents from the man who won't shut up (me!): the line between high-end PT systems and native systems is getting thinner and thinner. While PT was the only game in town for a long long time, Intel, AMD and Mac processors are readily approaching speeds which allow them to handle power-hungry plugins which at one time were exclusively found in the PT world... The fact that PT has those farm cards is what makes it so attractive, but why would anyone want to pay the prices they charge if someone could get an equivilant product on a home PC?
It seems that PT is playing a game of catch-up: for years it didn't have MIDI, this was added after sequencers like Cubase, Logic, Cakewalk, Vision (anyone remember this?) and Performer started adding audio and plugins as features; now PT supports Rewire, Digi cards have ASIO drivers to run with programs like Cubase and Nuendo, and they're bundling LE versions of softsynths originally designed to run on native systems that have been popular with a lot of people for years.
And now they're trying to tap into the home studio market because, I think, they see that people can make professional sounding tracks with other systems.
Take care,
Nick