Well, lets see if we can put this to bed.
You have been given some of the very best answers you will find. Re – read them. Don’t try and fudge the issue. 99% of the time what you are hearing is OPERATOR ERROR. You are trying to make “QRO”, into the issue, it’s not.
The chance of an amp “QRO”, in your words, sounding “BAD” “HOLLOW”, is probably less than 1 %. Other than that, the poor/awful/bad sound you hear, is from the equipment ( driving the amp “QRO” ), and the adjustment of said equipment by the operator. Now the amp could be effected by RFI, but that sound is usually pure distortion, not “HOLLOW”
Since you had to ask the question, it is safe to assume that you are new to the hobby/HF bands/ and to amplifiers, or as you termed them “QRO”.
So, since you are still getting your “sea legs”, here’s what you need to do, so you won’t have a problem with “QRO”.
1. Please read very carefully, the section of your owners manual, for your transceiver, on how to adjust the transmitter.
2. DO NOT, use any special, EXTERNAL, processors, EQ’s, or microphone amps.
3. Talk at the mike, not to the side of the mike.
4. Keep you face 12 inches or closer to the mic, 6 inches or less would be better.
5. Until you get use to using everything, DO NOT, use the speech processor.
6. Use the correct mic for the radio. That does not mean going out and buying some over priced, hyped up, gilded, mic. Use the mic’s the factory recommends. They will all sound just fine, when the radio is adjust correctly.
7. Think about buying a solid state amp. You will have more protection aginst blowing up the amp. Unless you pay attention to what you are doing you will run the risk of over driving a tube amp, risking costly damage.
8. Remember, this is ham radio. If you goal is to sound like your favorite FM DJ, or like some national news anchor, then you need to apply for the correct FCC paper work, and use the proper broadcast equipment. There are many reasons ( hundreds ),why ham radio will not sound like your favorite FM station, or TV anchor, the most basic of which is it wasn’t engineered to sound that way, period. A good number of the people that sound “HOLLOW”, think THEY sound just great. They don’t. Almost every radio out there can be made to sound very, very good, using basic mics, and proper adjustments.
Want to sound crappy, just god back up to number 1 and 2, and forget about them.
Lastly, go back and read:http://www.eham.net/articles/8069http://www.w8ji.com/loading_amplifier.htm
Now if you feel tic’ed off GOOD. Please don’t come back here re-asking the same question, in some re-phrased way, or re-worded.
DO, go back and re-read all the answers to your questions. If you do, then running “QRO”, will not be a problem.
Want to sound bad, have a bad QRO signal, well then just ignore all the replies, and do it your way.
Good luck in the contest.