If I dig a very deep whole in my yard and you do the same, we could almost meet in the middle, then you could try both..
If by Gaming phones you are talking about those that is connected via USB it will be hard to put an amp/DAC in the chain.
Otherwise you need to have the Amp/dac standing colse to your PC as there is no microphone in the amps I have heard of, sp the mic jack still needs to go into your PC..
Other than that there is no problems AFAIK, I only play Pacman and angry birds so I guess I am not a gambler..
You need to be able to take a digital signal to use an DAC, i.e USB/Coax/Optical from the device you want to deliver the sound, so instead of plugging your phones in an out, you will need to plug in the amp/dac instead..
The Fa003 (Jaycar digitec ?) is actually a very nice and good for value phone, it is by far the most neutral of the three, You would gain quite a bit with an amp/DAC for those also..
Do you want it to be different or like the fa003 in signature ??
2050 has the signature that comes closest to the fa003..
If you already got 2 pair of decent phone and are going to get a third or even fourth pair, it would be wise to get a bit more serious about the amp/DACs oherwise you will just end up like me with WAAAY to many amp/DACs, which also is fun, but you would save in the long run by spending a bit more than nessesary..
Meier Audio, Aune, HA INFO, Hippo, Audinst, Muse, little dot etc. etc. all makes good amp/DACs at an afordable price.