The one component that you wish you had not bought

+1 to the CV4004s.
Benz lukachek phono stage.  Dull as dishwater in my rig. 

This was a while ago, a Crown IC-150. Julian Hirsch raved about it in Stereo Review. Worse sounding POS ever!

Very top 7.1 CAMBRIDGE AVR and its matched top Blu-Ray player for my AV movies requirements ... 

I had a discrete AV system distinct and fully separate to my high-end 2-channel system. It sounded fine WHEN IT WORKED ... But Unfortunately it revealed itself to be a POS Chi-fi quality build rig that crapped out:
(A) the AVR suddenly failed twice withwhile under warranty, the first was a catastrophic sudden fail with a full motherboard replacement. The second was a sudden HDMI failure a year later three months prior to warranty expiry.  I sold it pronto after the 2nd crap-out fix.   and
(B) the matched Blu-Ray player failed suddenly and catastrophically  three months out after warranty expiry. The costs estimate to fix it exceeded the FMV of the unit so that was just scrapped .
(C) the stand-alone Martin Logan 7.1 Fresco and Vignette speakers and Dynamo sub were simply mothballed back into their boxes and stored away.

THE FIX TO THAT REGRETTABLE  SYSTEM PURCHASE

- Quality build NuForce AV-18 separate standalone AV 7.1 pre-amp / processor for movies and surround sound.
- quality build separate 3-channel Audio Refinement power amp
- Matched quality build separate 2-channel Audio Refinement power amp
- new standalone ARCAM FMJ Blu-Ray player for surround sound and movies
- AV preamp/proc feeds the direct pass-through feature in my 2 channel REGA OSIRIS integrated amp . This is the eventual "disposable" upgrade sometime later as CODECS change.
 - Separate REGA ISIS valve  cdp/ DAC strictly for 2 channel audio
- all REGA speakers (various models ) for either 2-channel or 7.1 as required by toggling across the inputs on the integrated amp.
- upgrade to a quality build Vandersteen subwoofer for movies only.

TAKEAWAY
(1) Well worth it to scrap the CAMBRIDGE ...(these was their expensive very top end units ) 
-- re-set to standalone separates was lots more money for sure but a whole quantum step up in performance ...and the  Improvements are not subtle.
-- All separate unit pieces now work flawlessly and each is built like a tank
-- I condensed the mancave  into one system instead of two 

(2) Chi-fi POS AV electronics failure reared its ugly head .... Pure crap build with a lock to ultimately fail so these type of quick-fix purchases never to be repeated again....full stop. Big regrets on that one ..... I ignored the time-honoured axiom that You get what you pay for ...

(3) The audio forums including AGON are teeming with Chi-Fi AVR failure complaints.., again full stop.

McIntosh MVP-871, bought as a demo unit at Magnolia A/V. It never worked right despite two trips to their repair facility. McIntosh had refused to offer any warranty as it was too long out of production. I see McIntosh universal players for sale often for substantial discounts to MSRP. When I inquire why, I usually find that they have been repaired/refurbished by McIntosh. Don't get me wrong, I like McIntosh but they don't seem to have perfected their players to the same degree as many of their otherwise fine products. 

VPI PLC  (aka imo - complicated light dimmer switch)

I can't believe even today I still see these things for sale at $250.