Perhaps you are holding the microphone too close to your mouth. Microphones are more sensitive than most people give them credit, and, if you sing at a normal voice level--or louder--with the microphone too close to your mouth, you run the risk of the microphone registering a very tinny sound. Since microphones work by converting physical vibrations of your voice into electronic signals, there is a finite amplitude (volume) that the microphone can transmit; excess signal is simply discarded or converted as signal noise. This reduces the overall clarity of the recorded output, and much of the lushness of the voice is lost. You need not sing quieter; simply move the microphone further from your mouth.
If you have ever performed, you know that any musical changes that are noted in the music and are interpreted by the musician must be exaggerated for these changes to be apparent. Similarly, whilst recording, any musical changes must be exaggerated. Great dynamic contrast (e.g. from piano to forte) should be made greater; strong vibrato must be made stronger; etc. This may account for the difference in the sensation in your skull and your reproduced voice.
If you tend to sing pop songs or something like them more than anything else, the natural tendency is for the voice to sound thin and, when it is reproduced, unnecessarily brash. You may notice that the upper portion of your throat may be quite sore after having sung for a while. This indicates that you are clinching your pharynx. A singer clinching one's pharynx is not unlike a brass player squeezing the mouthpiece against one's lips: it shrouds natural talent and diminishes the quality of the singer's tone. As such, if this be the case for you, you should practice singing something different. Songs that prove particularly good at relieving this problem are ballads: they are frequently slow and have rich chord structure. Do not skip a verse; do not skip any digression in the music; sing all parts with intention and determination. Philip Farkas advises French hornists to be aware of the mistakes that they make and work on correcting those mistakes--rectifying them by making them right thereafter. Similarly, you should keep track of the mistakes that you make and not allow a mistake to tarnish what is, ultimately, a fine voice.
Frequently, one will find that, after one's voice has been recorded, the reproduction thereof sounds "mushy"--the changes between syllables and, more noticably, between words are not clear. It may sound something like sliding up and down the music, not necessarily changing for each note. To rectify this problem, it is frequently helpful to read Shakespearean drama aloud. In Shakespeare's time, English had not been standardized (the English grammarians went into overdrive in the 17th and 18th centuries.); this cousin-like form of English is unfamiliar, as it only survives in colloquy to the extent of idiomatic expressions and particularly notable quotations. Therefore, it is a perfect training ground for emphasizing one's pronounciation: it is familiar to us, but only barely so.
We have discussed drama; but poetry is also helpful, being similar in form to song. Something with strong, rythmical feel (i.e. something with pronounced meter, rhyme, etc.) should be selected. Romantic (the period, not the genre) poetry, by and large, meets this requirement. The standard rules of English grammar are frequently bent and expanded in poetry, and so, if one do not properly enunciate, it will make little sense.
For most Western music, there are two different tuning systems: 12-TET [12 Tone Equal Temperament] and Just. In 12-TET, each note in an octave is spaced as far apart as either of its neighbors. This is not true of Just. Just was developed to make chords sound in tune, not just an individual note based on the tonic (first note of a scale). As such, the values differ slightly. If you tune your voice, be conscious of which system to follow. If you use a tuner, it will frequently register the tone in "cents," an arbitrary unit used to space notes, of which there are 100 between half-steps (contiguous notes of a chromatic scale). If you be tuning based upon 12-TET, then each note that you sing should register "straight up" on the display. However, if you be tuning base upon Just, then you should consult a conversion table to tell whether or no the note that you are singing be in tune. In general, only electronic and/or keyboard music strictly adheres to 12-TET, other performers tending to play notes that are said to "sound right." Bear this in mind when accompanying them.
Perhaps the problem is not with your voice. Many times, a recording suffers from being recorded in a room with poor acoustics. If your voice echo in the room in which you are performing, try mounting sound-deadening panels or hanging sheets in various places throughout a room.
Also, depending upon the method whereby you transmit your recorded voice, your method may be insufficient to carry a clear sound. If your microphone be far detached from the recording device (e.g. your microphone be separated by 25 or more feet of cable from the device performing the recording), the signal may have deteriorated along its path. Do not think that even though you have a cable which is said to be the best this is an exemption: for instance, TOSLINK cable (may be inserted into a plug called "Optical") can only carry a signal with its claimed integrity for about six feet; after that, the signal is subject to rapid and pronounced deterioration. Try being closer to the device performing the recording in terms of the amount of cable separating you from the recording device.
It is also remarkable how noises that sound so insignificant are so pronounced on a recording. For instance, if your air-conditioner be running behind your voice, you may hear what seems to be an incredible amount of signal noise even though it may sound so minute whilst being recorded. Try to silence as many subliminal sounds as possible: as I said before, microphones are very sensitive. Also, for things that are not strictly noise, microphones may interpret these things as sounds to be transmitted and recorded when this may not be the case. For instance, if you be recording in a significant amount of moving air (e.g. under a ceiling fan, in the wind, etc.), your voice may come across as ridiculously raspy. Similarly, keep the air as still as possible around a microphone. This effect is not limited to air; if the microphone rest upon a surface which has a tendency to vibrate, then the microphone may interpret these physical vibrations as induced by the voice, and it may interpret these vibrations as sound to be transmitted and recorded when this may not be the case. As such, one should take great care to ensure that the surface upon which a microphone rests is not vibrating.
Pushing the boundaries of human ability is not uncommon; in fact, in many regards, it is expected. This is not always true of the human voice. Increasing the range of the human voice in either direction can be accomplished, but only with time and within certain limits. Therefore, if songs that you sing frequently reach out of your range, feel free to adapt them so that this is no longer a problem. If you cannot bear this thought, then work at building your range SLOWLY. Your vocal chords must become accustomed to this unusual expectation of them, and to expect too much of them too quickly is to frustrate one's self and run the risk of perhaps permanent injury to one's vocal chords. If you would find occasion to build upon your natural singing range, do not do anything differently from how you have done it all along: do not tighten the throat, change the position of your mouth, the amount of space between your teeth, etc. In order to extend your range permanently, you cannot train yourself having used a method for singing in this newfound range different from singing in your normal range.
By the way, buying a different microphone, if you have already purchased one of good quality, will not assist your voice. If you be convinced that your voice is fine as it is and that you are obeying all the standard rules of performance and recording, it may be worth your while and your money to purchase a simple sound mixing board. This will help you emphasize certain elements of your voice and, perhaps correspondingly, diminish certain other elements.