Ensemble vs. Karaoke - Working with an ensemble is also important. I have found that singers who have spent their whole career singing to tracks have a really hard time singing with an ensemble. I am a fitness nut and spend four or five days a week at the gym. I often see many similarities between music and weight training. Karaoke is sort of like working with machines while singing with an ensemble is more like free weights. There are very few variables regarding machines. Basically there is one motion and you can't change very much regarding the exercise. While using machines, you use a very specific muscle. When you use a barbell or dumbbell, the variables always change. For example when you do a standing shoulder press, you will have to use muscles all over your body to keep yourself balanced. Besides your shoulders working, your core muscles are working hard to keep you stabilized and by changing your grip just a tiny bit, you will work different areas of your muscles. Just putting weights on the barbell uses muscles and lifting the bar to your shoulders before you do the actual press uses a set of different muscles. That is why body builders tend to use free weights more so than machines. Machines are better than nothing at all and in many ways are better for beginners because you can avoid injuries, but they aren't the choice of more advanced athletes. Machines focus too much on individual muscles while free weights focus on wide groups of muscles.
Singing with Karaoke has no variables, it is the exact same thing every time therefore you sing the same way every time. When you sing with a band, the variables change all the time, the dynamics, tempo, volume, even the individual parts change. This forces you to change and adapt. You can always tell the singers who are not used to ensembles, they want more monitor and might stick their fingers in their ears so they can hear themselves better. They have poor eye contact with the members of the band and have a problem giving cues for endings. They can't effectively count off the song. Singing with an ensemble will help you to develop singing energy to rise above the power of an ensemble. Karaoke doesn't have volume or energy so you can sing comfortably, maybe too much so. After all, if you can't get above the track, you can just turn it down. And if you can't hit the high notes, you can change pitch. You can't really do that with an ensemble so you have to develop a certain charisma and power. Just like weight machines are great for beginners, karaoke tracks are a fine place to start. But there comes a time when singing with an ensemble will help bring you to a new level.