You sure of that? Digital EQ affects the bit depth, so reduces fine detail, while a good tube amp operates in the analogue domain and detail is unaffected. The only analogue EQ I know of that is not only good but available at a decent price is the Schiit Loki and I intend getting one of those at some point for just this reason.
Already 16 bits has easily enough accuracy for human ear in almost everything.
(audio CD standard was based on thorough scientific studying)
And pretty much every sound card supports 24 bit accuracy for "lots of decimals to minimize rounding errors".
Internal processing in Windows audio stack might even happen with 32 bit accuracy.
And likely everything you listen has already gone through plenty of DSP in mixing and mastering.
Even physical "equalizer tables" and such might actually control DSPs, because digital form offers advantage over analog signal.
(of course if used algorithms are bad then there's going to be "side effects")
Remember that in analog signal chain every single component and piece of wire would need to be ideal/perfect (not going to happen) to avoid any side effects.
Just to even keep changes similar in both channels...
So in analog signal path every single component adds some amount of "rounding errors"/signal degradation/distortion.
It's like that taking photocopy of photocopy/copying C-cassette and using that copy as source for next copy.
Even those analog potentiometers for volume control always have their own side effect...
No matter what some claim that only "bit perfect" audio with analog volume control is accurate.
With enough accuracy/bits and proper algorithms digital processing can keep side effects equally minimal/lower.
BTW, even 8 bit signal isn't such automatically distinguishable "door slammed to face".
http://www.audiocheck.net/blindtests_16vs8bit.php