Filtering a signal to remove certain parts of the spectrum on the face of it (and intuitively) should reduce the perceived sound level. This is what common-sense would tell us. However, when it comes to the reshaping of sound with filtering, lowering the sound level doesn't always equate to lowering the peak level. Yes, the perceived sound level may reduce but on many occasions the instantaneous peaks will increase. This does not mean your ears or meters are lying to you.
Take a very simple repetitive waveform like a square wave. If you filtered it to enhance just the fundamental frequency you'd end up with a sinewave (pure tone) that is 27.3% higher in amplitude. This is a peak level increase of about 2.1dB.
When you hear the squarewave you hear the fundamental frequency and all it's harmonics because that is, mathematically how a square wave is constructed. Here is a techy (but good) article that explains how a squarewave consists of a fundamental and harmonics.
If you scroll to the lower half of the page you can see how they've constructed a squarewave from sinewave harmonics. Also notice in the formula (near page top), the 4/Pi - this, if you worked it out on your calculator = 1.273 and is the 27.3% higher in amplitude bit I referred to earlier.
So, in the case of a composite signal of a snare drum, many individual parts of the spectrum may be playing together and various filters may cause the peaks to increase and coincide. Remember the peak value on the meter only has to occur once in a few seconds to give the indication that the resulting filtered signal is bigger.
Here is a link to a quote from SOS magazine. The quote is an answer to a question related to this subject: -
Fundamentally, the filtering process changes the shape of the
waveform, so although there may be less total energy in the signal,
the peak amplitude may well increase.
END OF EDIT
There may be other reasons why it appears bigger but I hopefully have demonstrated that there is an absolutely rigourous mathematical reason too.