Being on the front lines as a manufacturer gives me an interesting perspective most of you reading these posts don't have.
One of the continuing themes I see, from this bird's eye view, is the tendency to blame the new guy: regardless of any facts to the contrary.
If we add a new phono preamplifier and the system now has hum, we blame the new piece of gear. Add a new Power Plant to the system and if something goes wrong, blame the new guy. Add a new cable and the system sounds bright. The list is endless.
In many cases folks are right - but in perhaps half the situations, they are wrong. It's an interesting phenomena, one that fascinates me.
What happens in many of these situations is we notice something that's been with us all along, for the first time, when we add a new piece of kit. This is because we've gone from autopilot mode to critical listener mode.
I first noticed this in myself when I got a car back from the body shop. The rear fender had been bapped pretty badly and it took several weeks of major body work to repair. When I got the car back, my first reaction was to be hyper critical about how it drove - after all, the best anyone at a body shop can do is get it back to original. It'll never be better. Funny thing is, I noticed that the car pulled to the left consistently. It hadn't done that before; take it back.
Turns out they never touched anything in the front and they kindly pointed out the problem (obviously from before) and fixed it anyway.
Point is, I never tested the car before the work.
Next time you get a new piece of kit in your system, take the time to really evaluate its benefits or downfalls - but first - give a critical listen to what you have before you make any changes.
It really helps.