With more oomph, I think you want more bass but not at the expense of any midrange or clarity at the top end? Knowing the kind of sound you like your music to have's the first step for me usually.
You're not necessarily tied down to the traditional amp/speakers/CD route either, at least, not in their traditional three box configuration, so it might be worth considering those options too if you haven't already.
Pre/Power amps, integrated/power amps, active speakers and offboard DACs could all form alernatives to your current set-up (just not all at once!).
I assume you can find out about some of this stuff independently. I suggested active speakers the other day as an alternative for another poster and was jumped on by someone who assumed I meant adding active speakers to a system which already had an amplifier (silly me). I assumed the OP had the capacity to do some research of their own and wouldn't need spoon-feeding chapter and verse. Such is the forum mindset at times and no offence meant.
Were it my money, I'd seriously consider active speakers as a viable option. Choose ones which have good powerful onboard amp power sections (so Acoustic Energy AE22 Actives - £850, Genelec 8040A - £1100, AVI ADM 9.1 - £1100) and perhaps add an offboard DAC to your CD73. Does your Arcam CDP have an onboard volume control? Some players do and this would mean you might do without a pre-amplifier to control volume, however if you need to select between more than one source (e.g., DVD player) then you'll need a pre-amp.
Actives more typically feature in recording studios, and some are unsuitable for the home being aimed at the music production sector where producers value a near ruthless neutrality which can make for an uneasy ride for domestic listener. However, the Acoustic Energy speakers received a cracking review in WHF a year or two back and I heard the Genelecs earlier this year (the 8030A, the model down) but was astounded by how good they were. Bass depth that was deeply impressive given the size of the speaker. The 8040A maintains this but has a more powerful onboard amplifier (90w to each of the amp and tweeter sections - ample by any other name!).
If you're keen to stick with the traditional separates route, I'd look at Harman Kardon's HK990 amp and the rather impressive partnering HD990 CDP (which I heard in the summer) and which work wonderfully well together. HK is a criminally underlooked brand in the UK and while their styling for their current range includes a batty volume control (and rather plasticky for my liking) the sound quality is very impressive. The amp is around £900-1000 depending on where you buy and is one of the best specced on the market currently.
Stello's DA100 Signature offboard DAC is another option, roughly £700 or so and this could go straight onto your Arcam player which I assume has suitable connectivity. Cyrus do another, albeit more expensive as part of the 8XPd amplifier. Opinions vary on Cyrus gear with some finding it too bright and this might be the case if you're upgrading in steps and running alongside your 685s. The Arcam CD73 uses a Sony transport I think, and was well reviewed when it came out, so this could be a good option for you too.
Speakers I'll leave out, but plenty of people will have their views on Spendor, Neat, ATC, ProAc and Monitor Audio RX6s on here. All I would say is that good though those brands are, there's a wider range available, so do also consider other options as well (Sonus Faber, Acoustic Energy, Mission and Opera to name but four of many more).
£3k though, a lot of fine gear out there for that money - lucky chap!
good luck!
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