Littlebear B4X Portable Tube Amplifier

I'm one of the older guys on Head-Fi, grew up with vinyl. Never did have the money for the exotic brands but I remember I really got into the early Dual 505 turntable, Goldring cartridges, and a bit later Musical Fidelity amps in the 80's. I got big time OCD over little T-Amps back in their day. I'm definitely an old analogue-man, lover of World Music and almost everything else musically. In July of 2019 I bought the Little Bear 4-X hybrid tube amp and have used it on and off ever since. Lately I found the Little Bear a good match with the Shuoer S12 Planar IEM and got back into using it.
A few weeks ago I got a message from Burson Audio asking me if I would like to compare the Burson V5i-D-2 opamp with the stock opamps. I've never been a compulsive Modder, but when necessary I'm up for it. The Little Bear looked simple enough so I found the idea interesting. I had no idea of any difference a new opamp would make to the sound, I'd never changed one before on the Little Bear. So armed with some small Allen Keys, some tweezers and a shaky hand, I got going. It turned out so simple to take the board out, take out the stock opamps and put the more substantial Burson's on.
The opamps had arrived a while ago, so I started to deliberately use the Little Bear 4-X most of the time to get back familiarity with the sound. That meant constant charging because the built in battery does not have the longest play time (about 5 hours). I chose a few songs to really mainly concentrate on... 'Stimela', live, Hugh Masekela and 'Shovelheads', Shriekback (Yep a bit left-of, but has a lot going on), and the great 'Grandpa's Interview', Neil Young. From Patti Smith, 'We Three', and also New Model Army's 'You weren't there'.
When comparing and A/B-ing IEMs there is a simplicity to hear the differences. Generally just take one off and put the other on. It takes just a few seconds. Even then there has to be the memory of the previous moments. The moments are close enough to get a fair idea of the differences. When changing opamps though there is more time involved in the change so the gap in listening is longer, so possibly more deceptive. It's useful to write keywords down to keep impressions fresh. So what I write here can be taken with a pinch of subjective salt, but is what I heard.
Before listening I left the 4-X to warm up for 15mins. First thing I noticed with the Burson, seemingly more RF interference. More sensitive obviously, but that can be good in the long run. Not a problem for me, maybe for some. For me once the music starts this old guy cannot hear the RF so no problem.
Compared to stock the Burson's are less generally fuzzy, and have a much cleaner sound. Leading edges of guitars and drums are more defined and precise, sub-bass is cleaner without losing rumble. A subjective feeling of musicality arises whilst listening with the Burson V5i-D-2's.
Patti Smith's wonderful voice becomes richer, thicker and smoother, yet cleaner in 'We Three'. Same with Hugh Masekela's voice in 'Stimela' and the instruments too. On 'Grandpa's Interview' from the 'Greendale' project, Neil Young has more resonance on the lower register guitar strings, and a kind of mini vibrato all the way through plus great cymbal crashes later in the track.
There is little doubt the Burson opamps are noticeably different in sound to the OG's. It surprised me that a little opamp can make such a difference. The Burson's are here to stay in my Little Bear and easily give me a large dose of extra enjoyment.

IEM used, IMR Splash of Gold open back, Spiral Dot L tips. Sony Xperia 5ii phone.

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"Great compassion
penetrates into the
marrow of the bone."
NAGARJUNA

Intro
For those not familiar with the Douk Audio Littlebear, a short introduction. The Littlebear comes in two versions, both portable, they are both tube amplifiers, one which is balanced, B4X and the other not balanced, the B4. For the purposes of this review, we are only concerned with the dual mono balanced version, the B4X.



Burson Audio, a leading audio brand has made various OpAmps used by manufacturers in various products and by enthusiasts for after market modification of products,. Burson have on this occasion brought to market the Burson Audion V5i-D-2.

Disclosure and Note
Burson Audio kindly offered me the V5i-D-2 free of charge for review purposes. In exchange I provide my honest opinion.

As always, all opinions I express here are my own with no influence from anyone. No one has editorial control or influence over the contents of this review. I make an effort to ensure that I give the reader factual information. I appreciate your feedback.

Point to note
An important caveat - The very nature of this operation, to disassemble, remove the original and install the Burson OpAmps and then reassemble the unit is relatively swift. Nonetheless, when considering the fact that one has to retain in memory the sound they last heard before the disassembly, it is clear that to retain memory of the original OpAmp may not be precise, and I can only claim to have retained a general memory of the B4X in its original form, which I have owned for over 3 years. However, short of having two units (one with the original and the other with the V5i-D-2) to review side-by-side, I have to rely on my memory.

My setup for this review
I paired the modified B4X with Fiio M11, Samsung galaxy Note 10 plus, the Mi Mix and I used UAPP, Amazon Music and Youtube Music as my music players.

The modification process:
Quite frankly, the modification process is a straight forward process. With the unit standing upright (the bottom being, where the on/off switch is, and the volume knob being the top) the BX4X has four screws, which require an Allen Key to unscrew. At the base there are a further 4 screws which require a Phillips screw driver to unscrew. Given the unit is made of two solid aluminium curved shells which sit snugly together with no additional fastener, thus the top and base screws effectively hold the unit together. Having said that, it seems to me the disassembly is fairly straightforward and require only the 4 top screws to be removed.



On removal of the screws the circuit board slides out quite easily and brings up the original OpAmps which can then be unplugged and replaced with the Burson Audio V5i-D-2. The entire unit disassembly, OpAmp removal, OpAmp replacement and unit reassembly process took me no longer than 10 minutes.

Warning: Beware the filaments (inserts) on the OpAmps are fairly thin and fragile, pull original out with care and carefully line up the V5i-D-2 before insertion.

The V5i-D-2 itself is approximately three times the thickness of the original, but clearly designed to fit with ease and has good clearance when seated properly in position.

Sound Quality
The original sound is, to my ears U-shaped with an undeniable tube flavour, which to me is warm. Install the Burson V5i D and the sound remains a similar signature but is cleaner and clearer. Another feature of the V5i is more noticeable micro dynamics and less noise.

What is without doubt to me is that the warmth of the B4X is maintained but with better defined bass notes.

At various stages it sounded as though the mids had been lifted beyond the original sound. The saxophone of Richard Elliot, on Deep Touch seemed to belt through with no hindrance.

The story of the headphones/earphones I used is as follows.

Note: Please note that, as stated above, I use an external Bluetooth DAC, namely the Taotronics TT-BA08. I do not benefit in anyway in mentioning any item in this review. My reason for mentioning all that I have mentioned is for anyone who wants to replicate the sound I speak of, to do so using the same equipment.

Earphones used:



Final E500:
Despite these being an entry level single dynamic set, with the burson V5i, they gave quite information with good clarity in the bass and mids but lacked air in the highs. That appeared to be more a limitation of the earphones rather than the opamps. The technical performance of these earphones on the B4X paired with the V5i were not exceptional but not bad at all.

Euge Groove - Chillaxin

TRI Starshines:
These were incredible on the B4X with the Burson opamps, out performing the sound from the Fiio M11 in the micro details coming out of the TRI Starshines, while giving well defined bass notes, and the mids did not disappoint. However, the best part of these on the V5i modified B4X is the sense of stage which was expansive with wonderful instrument separation.

Waldi Strecker - Midnight Ocean (Smooth Night Mix)




IMR Red 2:
The Red 2 are very easy to drive compared to the Starshines and the bassiest set in this review. Boy, did they come across as engaging and harmonic….they were hard hitting! The bass was quite prominent but the definition was awesome right across the frequency spectrum. Again there was plenty information and they almost sounded like they were a bright set.

Conclusion
The Burson opamp has revived a favourite portable DAC/Amp which I bought from Linsoul a few years ago. There are not many portable DAC/Amps in the $80 range much less many DAC/Amps which are so much fun for so little.

For those who already own the B4X, this inexpensive portable unit can be upgraded using the Burson opamps and Taotronics Bluetooth DAC for an additional $50 (V5i) and $40 (Taotronics). For those who have yet to dip their feet in the portable tube pond, well this your opportunity.

Considering there are portable DAC/Amps with tubes costing north of $2k, this is relatively inexpensive audio pleasure on a tight budget.

Enjoy your music!