God doesn't care about perfect melodies or perfect pitch for that matter...He doesn't even care if you sing flat...
God cares about what's in your heart...
Again, listen to the interweaving of the independent melodies in the four parts - and watch the shape of it in the score. THAT is an appropriate offering to the Lord of the Universe.
I listened...That's just man pleasing man...
But it is our duty to exercise our God-given gifts in His praise. Mr. William Byrd was a modest man, loved by all, and God's devoted servant in the face of much persecution. His brilliant use of the talent that God gave him (probably the greatest English composer of all time) has moved many hearts.
We should offer only our best, and then say, "We are unprofitable servants."