Comparisons of FIR Causal filters of type HRIR in Discrete Time and Frequency Domains I have just implemented a Discrete Time Convolution between HRIR filter at a range of angles. I also implemented an Overlalp-and-Add method and FFT and IFFT to compute the same convolution in Frequency Domain.
The HRIRs are the same measurements which are taken from a public database for both DT and Overlap-And-Add methods.

The input signal is an audio file and the output is supposed to be a 3D effect of producing a sound that moves in the horizontal and vertical planes for defined angle steps for both methods. The horizontal plane movement is a full circle at the level of the listener's ears from left to right and the vertical movement is a half circle from left ear to right ear at the level of the listener.

My questions are:

1) If I wish to compare the filtering done to each HRIR angle above in Discrete Time, is it beneficial to check the shapes, magnitudes of each HRIR angle and compare it against each other angle?

2) With regards to comparing the filtering done in the the Frequency Domain. What parameters should I compare? 

3) Does the FFT of the individual HRIR at an angle help to compare the results?

Note that I have only compared the quality of the sound in the output file in both DT and Frequency Domains.
These are the figures of filtering at certain times in Discrete Time and Frequency Domains