To summarize all this, we can see that the type of product you choose plays an important role in answering that question – “Can brainwave entrainment damage my brain?” My personal advice as a long-term user of the technology is to Be selective about what brainwave entrainment audios you download from the internet, and make sure to follow the instructions! 
When blended with musical sounds, brainwave entrainment frequencies induce specific states of mind, which are the result of those brainwaves, delivering them in pleasing and relaxing audio tracts for use with and without stereo headphones. For example, alpha and theta waves, because they exist at the borders between conscious and unconscious thought, are especially rich and useful for tapping into and stimulating subconscious processes.
Isochronic tones are the most recent and advanced method for brainwave entrainment audios. With isochronic tones, the same intensity is used for all tones, but they pulsate on and off at different rates. The speed, pattern, and rates of these tones can be changed and altered throughout the recording, and the brain will follow them into desired states. The use of isochronic tones opens up the ability to lead the brain into highly specific states, at specific speeds and intensities. This has opened up the doorway to producing both dominant and subdominant waves(i.e. an alpha brainwave state with subdominant theta waves), and the ability to lead the brain through different waves, at specific speeds (i.e. holding the brain in an alpha state for 10 minutes, then dropping it through theta for 20, and holding it in delta for five before bringing it back into alpha at the end of the recording.) This allows thousands of different possibilities in training the brain, and also makes the process of listening to these types of audios more natural, and more powerful. 
Monaural beats have similarities to binaural beats, but the two separate frequencies are delivered through a pulse pattern and mixed before they reach the listeners ears, resulting in the advantage of being audible without stereo headphones. However, using stereo headphones intensifies the effectiveness of monaural beats and is recommended for the best effect. 
Anyone who has sought out different methods for enhancing cognitive ability will probably have come across a technique known as Brainwave Entrainment. However, it is a fairly niche area of brain training, meaning that this form of stimulation is often overlooked in favour of more mainstream methods. The following outlines what Brainwave Entrainment actually is, how it is used, and some of the benefits attributed to it.
1. Compressed formats like MP3 do not retain the sound quality necessary for the brain to fully achieve brainwave synchronization – and are too inferior to effectively deliver even binaural beats downloads or isochronic tones properly, much less something as powerful as NeuralSync™. Our lossless audio entrains at the precise level guaranteed to induce the most potent response.
Every NeuralSync™ audio is recorded with full-range frequency sweeps that cycle rhythmically throughout the entire audio. The dynamics of the sweep are then additionally enhanced with simultaneous left-to-right channel crossing. Because of this augmentation, the effects are multiplied, the intensity is amplified and the brain is drawn into the mental state more consistently and powerfully than with the static methods of other protocols.
The brain has two hemispheres that operate somewhat independently from one another. The two hemispheric structures of the brain are connected by a large nerve, called the corpus callosum, which sends information back and forth between the two sides of the brain. In most people, the left hemisphere controls language, logical thinking, and analytic processes and the right side contains the centers for emotion, intuition, and non-linear creative thinking.
The implications and potential benefits of brainwave entrainment technology are staggering, and a seemingly infinite amount of doors have been opened to be explored.  This technology is highly useful in the self-help/personal development field in a variety of ways.  It can also be used to enhance NLP and hypnosis recordings to make the mind more receptive to suggestion.  Brainwave entrainment can be applied to help people fall asleep, to improve focus and concentration, or to relax.  Recent and modern experiments are also being held to see if brainwave entrainment may help  to treat and/or cure mental “disorders” such as depression or ADD.  One of the most common and popular uses of brainwave entrainment is to effortlessly induce deep meditative states.
PPPS. You won’t BELIEVE the amazing change that YOU are about to experience. I’ve seen thousands of individuals undergo powerful shifts in their consciousness as a result of using this program. It’s EMPOWERING, and it’s available right now after 10 years of intensive testing and refining. Discover the magic for yourself! Purchase the CD version, or the download version!

That is very interesting to hear. I have also been an avid user of Holosync for long periods of my life. Were you progressing through the levels? I do know that Holosync in particular is designed for each level to push the brain to grow a “tolerance” to its effects. Once this happens the brain and nervous system has reached a new level of resiliency and is ready for the next level of the program, where the carrier frequencies are lower and more profound effects begin again. Was this the case for you? If Holosync was not your bag, you may also consider trying out some of the newer brainwave entrainment products with isochronic tones and monaural beats (holosync only uses binaural beats) as many have reported that they work better for them.
Isochronic tones work by influencing your brainwave activity and they can’t directly affect the body. That said, the brain does control the body, so sensations and feelings can sometimes be felt in the body after stimulating your brainwave activity. Some people who are new listeners of this type of audio can sometimes feel tingling sensations in their body. Not everyone feels this and these sensations usually stop once you get more used to using the audios. Isochronic tones are considered as a safe technology. However, sometimes they can leave you feeling temporarily fatigued, especially if you listen to them for an extended period (hours) when you first start using them. If you felt fatigued, I would recommend using them for a much shorter period while you are getting used to them and ensure you are well-hydrated.
Isochronic tones work just the same in delta as they do in alpha, theta and beta and they are widely used in the brainwave entrainment community to help people sleep. Like you, I’ve also seen some websites saying they don’t work in delta, but it’s a bit like the game of Chinese Whispers, where someone makes a comment and then after it gets passed around and shared a lot the message gets distorted and appears to be a fact. I don’t know of any scientific reason why they wouldn’t work in delta. I remember some people talking about this on a brainwave entrainment forum many years ago. They were saying they found isochronic tones a bit too abrupt for using to help them sleep and they preferred binaural beats, as they thought they were a more soothing sound. That was just a personal preference shared by a couple of prominent forum members at the time and some people then took that as a fact for everyone. That’s where I think that belief originated from.

The functional role of neural oscillations is still not fully understood;[6] however they have been shown to correlate with emotional responses, motor control, and a number of cognitive functions including information transfer, perception, and memory.[7][8][9] Specifically, neural oscillations, in particular theta activity, are extensively linked to memory function, and coupling between theta and gamma activity is considered to be vital for memory functions, including episodic memory.[10][11][12]
×