A few things:
a) Electrolytic cap tolerances are typically +100%/-20%. In most cases, you do not want to run low, but running higher is almost inevitable.
b) Low-value caps (capacitance, not voltage) run usually +/- 10%, but in most cases unless directly in the signal path, 20% is OK. If in the signal path, even a swing of 5% may make an audible, but slight, difference.
c) Pathway together with placement are critical for low-value caps. I restore vintage radios as a hobby, and misplacing a cap (moving it to close to the wrong thing) can make a difference. Generally, I take a picture of the "before" state before diving in for that reason. Using an axial ILO a radial (and vice-versa) may also make a difference.
d) Then, there are cold-solders, solder-splats and cuttings lodging across traces. Generally, I will shake whatever I am working on, blow it off with canned air after using a soft brush across all accessible surfaces to free any bits that may have solder rosin on them (making them sticky).
Some general advice on capacitors: It is important to check even new ones before installing them. Never mind what you have been told-or-sold. I keep a good ESR meter and a full-voltage cap checker such that _every_ electrolytic gets checked before being installed for a critical application. I will also check my low-value caps on arrival and class them as =, + or - depending on how they fall on the tolerance range. A Sharpie does that even on the tiny ones.
Voltage: DO NOT EVER go below OEM rated voltage. for 5 - 20V, it is OK to go as much as 400% over voltage without serious consequences. So, a 20V cap ILO a 5V cap is perfectly fine. 20V to ~, I try to stay within 200% of rating. There is some logic on why this should be that I accept - and it is easy enough to do anyway.
Note also that if you replaced _EVERY_ cap, it is quite possible that you replaced caps on the bias circuit - and your artifact may be as a result of changes to that circuit based on cap changes. You will need an alignment tape and bias instructions to correc this - something that is good to have and good to know how to do in any case. Alignment ~~CAN~~ be done by ear (and a fine pair of headphones) to an extent - but instruments and a tape are helpful. I have gotten very good at it over the years given the scarcity of quality alignment tapes these days.
Good luck with it.
Melrose Park, PA