Would a desktop amp be of any help?

Here is what I have right now:

Source: M-Audio 2496 PCI Card. Plugged in are 1. ATH-AD900 or Audioengine A2.

Basically, I'm looking for some advices on what to get next to maybe get more out of the Headphones (and maybe even the speakers at some point). Is there a desktop amp that could be a proper purchase? I'd be certainly more inclined to make a purchase for the headphones as I use em more than the speakers for some reason. I also know that the AD900 can be run properly without an amp. But could an amp make any difference with that audio card I have? Could the purchase of an amp like let's say the Violectric V200 be overkill (I have no plan of purchasing higher-end headphones in the upcoming months, but who knows maybe some day?

What could be a good gain for the money?

I also heard I don't need a DAC with such an audio card. Is that true? How about the Matrix m-Stage amp?

Thanks forever fellow head-fiers!

ANother thing: I'd like to be able to switch from headphone to speakers without having to go unplugging/unplugging behind the computer case, can the MK-5 be a good purchase? I know there are quite a few questions in this but I'm quite confused at the moment.

Thanks!

Alex

Some adapter with white and red channels that I plug the headphone and speakers into. I'm not sure where I got it though, prtobably on an old dvd player or something.

I honestly believed that the card had one set of output and one set of input, otherwise, why would it be made for recording? Please enlighten me on this. Also, where do I buy more of these red white cables that I currently am using? I am quite visual so I probably need something visual to understand anything out of this.

Currently I have the card with 4 plugs. White-Red-White-Red

" first white-red connectors and linked thru an adapter and thatM's where I plug my headphone/speaker. 2 other plugs arent used, but they should be inputs rather than outputs so I don't think I could put anything there. What would be a possible solution?

Thank you. Where do I get RCA cables? Also, how can I easily switch from speaker to headphone this way? WOuld you see how it could be done?

I'm still not sure what RCA cables are though, even after reading about them. How is called the adapter I currently have called? I'd also like if someone could PM me about what I'd need to purchase exactly to setup things. Having an amp seems like a good idea, but I'd also like to switch easily from speakers to headphones and vice-versa. There are some many types of cables I'm quite lost and wouldnt want to buy things I will not use. :P

Thanks!

Thanks. I read about the Fiio amps, but I was unsure as they only run from a battery right? I wouldnt want an amp that runs from a battery. Just saying.