'Upgrades' that went wrong.

I'm struck by how often people caution great care when advising others about upgrading, which I am sure is sound advice (NPI) - often it's suggested that X might not work with Y, or with the room size etc. I am not questioning the soundness of such advice, but I can't say I've ever regretted upgrading and very little of what I have bought has been demoed at home - several bits were solely off the backs of reviews or sourced from eBay. So, have I been lucky? Have you bought stuff that you have regretted*?

(* By which I mean that overall you wish you hadn't bothered, rather than 'item X was better than item Y in most ways, but not all.')
 
I can't say I've ever wished that I hadn't bothered as every change in a system is interesting in different ways, but I have experienced the disappointment of 'upgrades' that haven't really delivered for me and my needs. I've had decidedly average experiences of moving from budget to mid-level kit and often found the expected improvements underwhelming.

I run two systems - one in the lounge and one in the bedroom - and I'm now reaching the point where I'm happy for them both to be well balanced 'budget' systems that deliver the music rather than distracting from it.