I am a late arrival to this thread which is interesting but, I think, somewhat unfair.
I think it would be fair to say that Arcam is not a hi-end brand, but a mid-market brand, at least until fairly recently in hits history. The most expensive stereo components they produced in the mid-2000s (probably their peak success period) were the C31 pre (£1,200 retail), and the P1 monoblock (£1,100 retail each). That put their top-flight amp at £3,400 retail which, whilst serious money for most people, especially in the mid-2000s, doesn't get anywhere near where you can go with Naim, Krell etc.
I would say in the early-to-mid 2000s, stereo component quality was very good. the Alpha, DiVA, and FMJ lines included some very nice kit. The CD23 and CD92 players, with their licensed dCS ring DAC, are still very nice sounding players today if you can get hold of them. The A85 was a very highly regarded stereo amp at the time, and is still highly regarded now.
A/V was initially supplementary to the stereo kit. There was a single A/V receiver on sale - the AVR100, AVR200, then AVR300 etc. The stereo kit was also designed to accept multichannel cards/additions to the chassis. The FMJ A22 could accept a full AV processor card add-on, with digital inputs, DACs, switching etc. This was scaled back for the A32, A85, and A90, which could accept a multichannel input card but no DACs or digital processing.
A great experiment was undertaken in the early 2000s where very significant R&D was poured into a multichannel processor and power-amplifier, which became the AV8 and P7. From today's vantage point, many of the engineering challenges of home cinema have been solved (although manufacturers have created entirely new ones to justify new products), so it is easy to forget how bad home cinema kit was in the early-2000s.
The AV8 'solved', for the first time (partial exception of the Tag McLaren AV32R) many of the problems of decent multichannel pre-amps, including a beautifully designed DAC stage with a crystal PLL, a SMPS where the switching frequency was synced to the sampling frequency of any incoming digital signals (to eliminate audible switching noise, novel then but commonly used now by Lyngdorf etc), broadcast-quality video switching and processing and, finally, a multichannel pre that could turn its hand to stereo duties successfully and not sound unlistenable.
The P7 was also a very impressive achievement. It adapted the power-amp stage of the very successful A85 stereo amp, managed to fit seven individual amp units into a large (albeit fairly good looking) chassis, and connected these to a beautifully designed PSU. In the early 2000s, multichannel power amps almost invariably could not sustain significant power output into five or seven channels. The P7, like the AV8 for pre-amps, successfully 'solved' this engineering challenge and was able to sustain very high power outputs into seven channels simultaneously.
These two bits of kit were enormously successful. The AV8, I think, retailed at £3,300, making it by far the most expensive component Arcam had produced at that point. It underwent a mild update, I think in 2006, to become the AV9, which added HDMI switching and some circuit adjustments. The AV9 was also very successful, and retailed at £3,600. It is telling that, despite the high entry price, the AV8 and AV9 still very frequently appear on eBay, which gives some indication of just how many of these sold and are still in circulation.
The problems came when Arcam tried to repeat the success of the AV8/9. Again, very significant sums of R&D were poured into developing three successor products, the AVR500 and AVR600 (both AV receivers), and the AV888 (an AV pre/pro).
I think it is fair to say, all three products were a disaster. There are very widely documented problems. There seemed to be two main problems. The first was that the AVR600 was Arcam's first venture into class G power amplification, but it created very significant heat-management challenges, which were not successfully overcome at the design stage and resulted in very high rates of product failure. The second was, the A/V market had become infinitely more complex since the AV9, and people expected things like an on-screen display (via HDMI) that could overlay upon the source picture, automatic setup routines, room equalisation, internet radio, network media players, plus great sound quality. I think the complexity just became a bit too much for Arcam which, at that time, was a mid-sized company that did not have the know-how of the major Japanese brands with whom they were competing (particularly Denon and Marantz who produced feature-heavy kit).
There were some positives - the AVR600 and AV888 both 'solved' a very significant engineering challenge, of avoiding jitter in audio signals transmitted over HDMI, and the basic sound quality (when they worked) was outstanding. However, the HDMI switching did not work properly, both models were prone to unexplained freezing and shut-down, and there was no video pass-through and they corrupted video signals, some of which became unwatchable.
This, sadly, came at almost the same time as the 2008 financial crash, which killed aggregate demand for home cinema in particular, many of the purchases being funded by credit.
From there, a series of poor decisions followed. There was an attempt to offshore the production of most equipment to China. However, if you don't know what you're doing, you can very easily get burned by attempting this, as Quad found when production shifted there after their acquisition. The kit that came back was simply not saleable and, at tremendous expense, the production had to be on-shored again to the UK. This was a very expensive mistake.
So by this stage you had a company facing a shrinking sector during a steep recession, that seemingly tried to compensate by cutting production costs, but where this attempt created far more problems than it solved.
Some strange and desperate attempts were made to shore up the bottom line, almost all of which were a failure. I remember at one point they released a strange, add-on battery/DAC pack to stick on an iPhone, supposedly to improve the sound, which was not a success. Some speakers and 'lifestyle' products were introduced, particular a Solo line, the early models of which had very high failure rates. Some blu-ray players were released under the Arcam heading, but where design had seemingly been entirely outsourced and they were some of the very worst products on the market and were outperformed by a Playstation games console.
I think the rest has been covered in the thread already. A series of acquisitions has now left them part of Harman group. The product line has dwindled somewhat and seems very much focused now on lifestyle and home cinema products.
John Dawson, as I understand it, was effectively forced out of the company he had founded, understandably given the series of errors in the late 2000s which must have threatened the viability of the company.
I think it is now led by Charles Brennan, who has some hinterland in lifestyle products, although I'm not sure how successful these were.
I can't say I'm tempted by any of the new kit, but there are some excellent options on the used market. I have seen AV8s go for £100, which is simply insane given the value of the engineering inside. The A32/38 are both excellent stereo amps, and the C31 is a very transparent pre and very easy to use.
I am a bit saddened by this story. What was once a great British success, founded by two Cambridge graduates in the 70s, is now just another subdivision of a multinational with little that is recognisably British about it.
I should add, for many years, Paul Miller, Editor of HiFi News, and President of EISA, used the AV8/P7 as his reference amps in his personal system. He eventually shifted to an AV9 and six P1 monoblocks. I would say it is one of the highest compliments a manufacturer can be paid that somebody of Paul's achievements relies on their kit as a reference, and speaks to the quality of Arcam products in the mid-2000s.