Getting back to the OP's question...
Speaking in general terms, the biggest recent advances have been in DAC chips and computer transports/interfaces. Apart from that, good electronics, as always, need lots of current regulation and good output stages...that means stuff like big, heavy transformers, capacitors, higher quality op-amps etc. extra regulatory circuits etc. -- I doubt the cost of these components has altered much. If these things didn't matter, there would be no £3000+ CDP's/amps on the market.
So I would guess that modern budget CD players have closed the gap a bit, budget amps maybe slightly less so.
The Marantz is reassuringly heavy. Following the above logic, you might be struggling with a mini system.
Food for thought: given that we are all trying to get something for nothing, perhaps price is a good guide. As someone posted earlier, the used price of your Arcam gear is about the same as the new Marantz. So you'd expect roughly the same sound quality.
As far as speakers go, I read somewhere a report of a magazine comparison of a current Dali speaker with an equivalent 20+ year old model. I think the conclusion went along the lines of the new model being only very slightly better. More striking was the different presentation, which reflects the "fashion" of the day.