It's a good idea to step back a bit and think dispassionately about what you're trying to achieve here, without reference to your current system.
1: What's the biggest speaker you can fit in the room?
2: Will the budget stretch to a really good big speaker, or only a good small one?
As a helpful rule of thumb: the smaller the speaker, the more it benefits from being active. There are no good small, passive speakers - not compared to a comparably priced active pair.
The AVIs have been loudly publicised, and (ironically) the makers have found a way to embed the idea in buyer's minds that they are cheap. However, in concept they are simply OK studio monitors - which are widely available in the pro audio world for much less money. If you need a good, small active speaker, there are many very appealing choices from manufacturers such as Adam, Focal, KRK, Swans, Dynaudio, Genelec, et al: check out an online retailer like dv247.com.
To illustrate the value equation: Focal's top Beryllium tweeter is found in two 'domestic' passive small box speakers: the Diablo Utopia at £9000 and the 1008Be at £2700. Marketed well under the audiophile radar, Focal sells the Solo 6 Be - same tweeter, with the W-Sandwich mid/bass driver appearing in a number of big-ticket Focal designs - activated with four high-quality bespoke amplifiers - for £1500 a pair. If you drove the 1008Be with £2K of amplification and £500 worth of cables, at £5K+ it would still struggle to outperform a pair of Solo 6 at £1500. I know, because we tried!
If you can make space for big drivers and big boxes, you may be able to get away with simple, low-power amplification (unless they're panels). If you only have room for little boxes, you may need to invest in power.
Ultimately, the room and budget will dictate the speakers and amplification. The amps/speakers will then dictate the source: if they err on the side of brightness or leanness, an injection of drive, warmth and presence from a preamp may be required. If not, the transparency gains of a DAC with volume control direct to monitors or amplification might be preferable.
Finally, the DAC will choose the transport: if your favoured DAC sounds better via USB or Firewire, you need a computer. If it prefers SPDIF, you need a seriously good clock. Not the kind you find in a cheap streamer. Again, it's hard to find a reason not to use a computer for this job: even an off-shelf netbook offers much greater flexibility and (ultimately) performance than a locked-down proprietary lifestyle gadget . . .
On-board storage? Check.
All sample rates handled up to 32/384? Check.
Remote control via smartphone or tablet? Check.
NAS/network-compatible? Check.
Completely upgradeable? Check.
Affordable? From £150.
Compatible with every internet radio station? Check - try that with a Squeezebox.
Compatible with BBC iPlayer for radio and TV? Check.
Compatible with Spotify, MOG, the Cloud and all other streaming services? Check.
Compatible with FLAC, ALAC, AIFF, WAV, APE, OGG and all other file formats? Check.
Compatible with YouTube and all other video-streaming services? Check.
What's not to like??!