Also, even though these are "mastering plugins" a lot of this shit can be used on single tracks (especially drums)
Actually the Pultec is more the other way around... it is mainly used for single traks but is also great on the 2 bus & can be used for mastering...
In addition to working well with single trak applications, the Fairchild is widely used as a buss/submix compressor ... but I personally wouldn't use it for master-bus compression... Some have used it for mastering, I wouldn't though... but as they say in the audio community: YMMV
Not sure about the Opto-Compressor... but if it's like an LA2A (one of the most popular Opto-Compressors of all time) it's attack & release settings will not be fast enough for mastering purposes... although it could be used in mastering with the compression bypassed so that only the gain is engaged for 'tube-driven flavor'... but it looks like it offers a wider range of controls, similar to a Summit Audio DCL-200... If that's the case & it offers fast attack/release settings, it could be used for mastering... but don't expect the results to compare to those of which a real analog optical unit is being used lol
It looks like the rest of the T-Racks' line can be used for mastering,
The Brickwall Limiter, Linear Phase Equalizer, & Complete Metering Suite look ideal for mastering, but as I said before, I would stay away from the yellow ones lol
If you're looking for a plug-in compressor to use for mastering -I would recommend one that offers faster attack & release settings, such as UAD's Neve 33609 or Wave's API 2500...
Haha - I killed some good time with this post... now it's time to get ready for lunch!!