I think the options come in two flavors:

1. An external DAC into which the powered speakers are connected. These connect to the USB port and then have output from headphone jacks or RCA. Consider something like AudioQuest DragonFly v1.2: $149 $$$ or Cambridge Audio DacMagic XS: $199 $$$ You can get more expensive ones, but they might be pushing past the speakers and source material at that point.

2. New speakers that have an integrated DAC. These include AudioEngine or KEF X300a.

All of these DACs will play audio files better than standard MP3 or CD (44/16). If you want to take advantage of those sources, you also have to use an iTunes plugin like Audirvana Plus. You can get the higher-rez tracks from HD Tracks and a number of other download sites.

Hope this helps.

Scott

Hey,Mike!

I'm fairly new to higher end audio too. I'm also using Klipsch 2.1's with a late '13 iMac and recently added an Audioquest Dragonfly 1.2 and Channel D's Pure Music program (channld.com). They give you a 15 day free trial then you can buy it for $129. It was recommended on Audioquest's website. They have instructions on how to set up your computer for audio too. audioquest.com

An external DAC and powered speakers are the way to go. The Audioquest Dragonfly DACs are designed specifically for this application and Everone loves those Audio Engine speakers. JBL makes a few real nice pro speakers which will be in your price range.

If you can expand your budget, and I know that isn't easy, but check out the Dynaudio XEO 3. It is a really sweet, highly flexible set of speakers. I listened to them while I was demoing the Excite line of speakers and the sound quality is amazing but they are $1199. The key though is they are wireless.