The 614 is a very musical player, even in stock form. But it is a little bass-light and it lacks solidity, substance and colour. And it isn't the most lifelike performer. There are some very simple mods you can do in order to get a lot more from this player. These tweaks also work for other lightweight entry level CD players.
Above is the Philips CD614 in stock form. Behold the empyness... It is almost 100% plastic but due to the sidewalls, it doesn't bend. Still, it can do with a fuller bas and a more solid sound. To be honest, I wouldn't have thought this player was so special, let alone of modding it myself, if a friend didn't come over with his modded CD614. We did an AB comparison which made my player sound thin and gray in comparison. Sure mine was fluid and airy and refined, but it was nowhere near as full-blooded as the modded CD614. So, off came the hoods to reveal what had been done.
Here you can see the damping pads applied to almost all walls of my player. On the underside is a metal flap spanning a large area of the player, revealing the underside of the circuitboard. In standard form, this flap rattles. Not so anymore after applying damping material. The bottom picture is of the hood, also covered with damping material. The places left clean are where the transport clamping mechanism rests when the drawer is open. The tolerances are that narrow.
Even when only applying the damped hood to my otherwise undamped player, already it sounded fuller and more solid. This gave me the courage to go all the way.
With these damping pads applied everywhere, the player sounds much more solid, with a fuller bass and a calmer, richer midrange.
But there's more you can do. It's an old trick to disconnect the headphones, supposedly because this circuit puts extra strain on the already weak output stage. I've never put much thought into it but this time I just did the test. Sure enough: disconnect the headphone section and the bass articulates better, sounds faster and the midrange opens up and the whole becomes more rhythmic. Reconnect it and the sound mellows out but not in a good way.
Lastly, or actually this should be done first, is the installation of an IEC inlet. This not only allows the use of big fat cables, but also bypasses the otherwise very thin conductors inside the Philips-8-style connector. With the CD614 this is easy due to the plastic outer wall. Just desolder the 8-connector and drill the outlines of the new to be attached IEC inlet into the chassis. Then gently connect all holes. Then use a sharp knife to smooth the ragged edges. Don't worry too much about it, after installing the inlet, all will seem perfect.
After the mods had been carried out to my player, we did another comparison and sure enough, the players now sounded much alike! Sure, they don't become a Marantz CD11. But they come way closer than they should do, especially if you consider the modest original cost of around 300 euro! The biggest difference between a modded CD614 and the reference Marantz CD11 is in the luxury department. The CD11 doesn't sound more detailed, but it has more meat on the bones, a fuller, deeper bass, a wider soundstage with better separation and better focus.
After these easy mods there is more you can do but it will involve taking the player completely apart and removing the transport and circuitboard, then replacing and adding key components such as better diodes and capacitors and such. A lot is possible here, but it is difficult to choose the perfect component from vast amount of brands and types that are available and it is easy to make mistakes. Luckily, for this a friend comes in handy. He has an engineer background and knows what he's doing. Recently he came by with his re-modded CD614. It was basically the same as mine, with damping pads, headphones removed and IEC inlet. But he had also replaced various components inside, resulting in a very disappointing comparison... for me that is! Compared to his player, mine sounded once again gray and unsubstantial. What's more: his player now had superb soundstaging, with lifelike 3D portrayal of voices in the room, beating even the Marantz CD11LE on that aspect.
Note: the older, full aluminium-cast Philips and Marantz players don't need extra damping, they already sound luxurious and smooth. In fact, damping them would most likely shift the balance in the wrong direction. Disconnecting the headphone section however is always a good idea.