Quality speakers and Audio card allow quality vocal reduction
When you are trying to vocal reduce a song, you must keep this very important point in mind. There are several real differences in the audio output channels between your computer to your Karaoke player.
1. The Speakers and Amplifier you are listening to on your computer. If you have cheap multi-media speakers, you may not be able to hear low and high frequencies that you could remove if you heard them. This is a well know problem that is addressed by all professional studio engineers. You need good quality Near Field monitors to do an excellent job. I'm not saying that you will do wonders with vocal reduction simply by having better speakers, but I am saying you cannot remove frequencies you cannot hear. Thus, you probably will do a better job with better speakers. Try using the same amplifier and speakers on your computer that you are listening to on your Karaoke Player.
2. The Equalization settings on your Karaoke Player if there are any, might be boosting the bass or treble so it amplifies the residual echo frequencies. Vogone adds bass and treble boost so you don't want to boost them more in a Karaoke Player. If there are no EQ controls on your Player, this point probably does not apply.
3. The Digital-to-Analog converters on either device - your audio output in the computer, and the output in your Karaoke player - can affect the quality of audio you hear. Regretfully, we all want to believe that even the cheapest audio card is so wonderful, and so rich and full of all audio frequencies with no coloration of the... balderdash! The truism "you get what you pay for" carries a lot of truth in the audio field. Specs are just that... paper specs to make you feel comfortable to buy it. A better quality sound card compared to built-on audio on the motherboard will probably make a difference in what you hear. If the A/D converters and re-creation filters are poor performers, the highest quality speakers and amps in the world won't make a bit of difference.
Improving the quality of your audio listening environment will directly affect the quality of vocal reduction you can do, when the reverb echoes are not very loud. If they are loud, there may not be much you can do. However, with poor speakers and audio, you won't be able to do as good a job as otherwise. That's a fact for sure!