Now for the Big Boys...

Right. I like the LXMini. Could it be better? Apparently yes - there are various flavours of subwoofer available, all of which offload the (fairly small, TBH) lower mid/woofer for the last couple of octaves, and thus allow it to perform better. The SEAS drivers are pretty amazing (see here for some info on that), but the laws of physics will not be denied!

The choices are:

1. Relatively cheap omni subwoofers in 1 cu ft boxes - ok, but does their directivity or lack of it really match the carefully planned LXMinis? They're not a Linkwitz design, but from one of the guys on the OPLUG forum, people seem to have good results, but they would say that! About £130 for the chassis speakers (Peerless 830668), so a bargain
2. LXMini + 2 subs - these are from the Linkwitz design stable, and require the stonking Seas L26RO4Y D1004-04 woofers, at a wallet-busting £370 the pair!! However, they are dipoles and thus more amenable to room placement and more fitting with the LXMini directivity
3. LXStudio - again, from the SL stable, basically the LX521 woofer setup running in parallel to the LXMinis; these require 4 of the aforementioned WFW (Wallet Busting Woofers) at £740, and thus very much a nice to have... Again, the directivity is more fitting with the LXMini

All of these require 

• 2 more DSP outputs i.e. 2 more than I currently have, bummer
• 2 more power amps - now those I do have! The trusty Sony has two spare channels, hurray! You'd almost think I planned it. I don't have enough  power the LXStudio, since that's 2 massive 4ohm woofers per channel

DSP options include, but are not limited to:

1. MiniDSP 4x10HD: SL's choice, a very useful bit of kit, which includes analogue and digital inputs, volume control, selection between multiple stored configs; however, it's another WBO (WB Option...), at a stonking €650 from Audiophonics (not including shipping, but no customs duty (yet!), or $500 direct from miniDSP, in which case no idea about customs, but certainly VAT i.e. $600 before any customs/shipping! No. Not this time.
2. MiniDSP 2x4: Supported by Dave Reise on OPLUG, this is another of the DSP units I already for this project, paralleled by using one each for Left and Right channels, so it gets the same analogue input as the current one. Fairly cheap option, €85 from Audiophonics in board-only form, or boxed from CPC for £95 as last time. This gives me a total of 8 channels of DAC/DSP, which is plenty.
3. Hypex DLCP: excellent 6-channel DSP from these guys, but requires some building work; it has 6 (6!) analogue inputs (balanced - super!), USB/Toslink/SPDIF/AES-EBU digital inputs, loads of horsepower, and it's the basis of a much superior setup, including the Magic521 Powerboxes. It's about £530, without shipping and a good box to put it in. Hmm. I can also get it from Magic521 with the DLCP config file already loaded. If I was starting from scratch, or thought it would sounds loads better (it might :-( ) I'd be tempted. 

I've purchased the LXMini + 2 and Studio subwoofer plans, because they're fairly cheap ($55). Call me impulsive, but I've also bought a miniDSP 2x4 board from Audiophonics in France. Hey, useful anyway, right? It's a good way to try things out, without the massive expenditure of the other options. 

I've also purchased, because it looked interesting, and provides an alternative input mechanism, 

• A miniDSP miniDigi; this provides a digital input to the miniDSP 2x4, resampling the input to 48kHz using standard chips. I'm not sure if it does more than 16 bits, that would be interesting, but I think unlikely
• An Audiophonics digi+ for RPi; this provides a digital output capability for a Raspberry Pi, using S/PDIF or Toslink, and therefore avoids a DAC/ADC cycle when using RPi with the digitally-enabled 2x4. Worth a try, and I can in principle use both inputs with a bit of switchery in the 2x4

The miniDigi also provides a dual 2x4 capability, in that cunning use of its internal switching matrix and outputs will allow me to drive the two 2x4s from a single digital input, in fact that's the only way to do that. Some cunning-ness required, but hey, let's keep this complicated.